Roy Jenkins described it as the most significant since Gladstone's in 1860.

Lloyd George was born on 17 January 1863 in Chorlton-on-Medlock, Manchester, to Welsh parents, and was brought up as a Welsh-speaker. He is so far the only British Prime Minister to have been Welsh and to have spoken English as a second language.

His father, william George, had been a Teacher in both London and Liverpool. He also taught in the Hope Street Sunday Schools, which were administered by the Unitarians, where he met Unitarian minister Dr James Martineau. In March of the same year, on account of his failing health, william George returned with his family to his native Pembrokeshire. He took up farming but died in June 1864 of pneumonia, aged 44. His widow, Elizabeth George (1828–96), sold the farm and moved with her children to her native Llanystumdwy in Caernarfonshire, where she lived in a cottage known as Highgate with her brother Richard Lloyd (1834–1917), who was a shoemaker, a minister (in the Scotch Baptists and then the Church of Christ), and a strong Liberal. Lloyd George was educated at the local Anglican school Llanystumdwy National School and later under tutors. Lloyd George's uncle was a towering influence on him, encouraging him to take up a career in law and enter politics; his uncle remained influential up until his death at age 83 in February 1917, by which time his nephew had become Prime Minister. He added his uncle's surname to become "Lloyd George". His surname is usually given as "Lloyd George" and sometimes as "George". The influence of his childhood showed through in his entire career, as he attempted to aid the Common man at the expense of what he liked to call "the Dukes" (that is, the aristocracy). However, his biographer John Grigg argued that Lloyd George's childhood was nowhere near as poverty-stricken as he liked to suggest, and that a great deal of his self-confidence came from having been brought up by an uncle who enjoyed a position of influence and prestige in his small community.

Articled to a firm of solicitors in Porthmadog, Lloyd George was admitted in 1884 after taking Honours in his final law examination and set up his own practice in the back parlour of his uncle's house in 1885. The practice flourished, and he established branch offices in surrounding towns, taking his brother william into partnership in 1887. Although many Prime Ministers have been barristers, Lloyd George is to date the only solicitor to have held that office.

By then he was politically active, having campaigned for the Liberal Party in the 1885 election, attracted by Joseph Chamberlain's "unauthorised programme" of reforms. The election resulted firstly in a stalemate with neither the Liberals nor the Conservatives having a majority, the balance of power being held by the Irish Parliamentary Party. william Gladstone's proposal to bring about Irish Home Rule split the party, with Chamberlain eventually leading the breakaway Liberal Unionists. Uncertain of which wing to follow, Lloyd George carried a pro-Chamberlain resolution at the local Liberal Club and travelled to Birmingham to attend the first meeting of Chamberlain's National Radical Union, but he had his dates wrong and arrived a week too early. In 1907, he was to say that he thought Chamberlain's plan for a federal solution correct in 1886 and still thought so, that he preferred the unauthorised programme to the Whig-like platform of the official Liberal Party, and that, had Chamberlain proposed solutions to Welsh grievances such as land reform and disestablishment, he, together with most Welsh Liberals, would have followed Chamberlain.

On 24 January 1888 he married Margaret Owen, the daughter of a well-to-do local farming family. Also in that year he and other young Welsh Liberals founded a monthly paper Udgorn Rhyddid (Bugle of Freedom) and won on appeal to the Divisional Court of Queen's Bench the Llanfrothen burial case; this established the right of Nonconformists to be buried according to their own denominational rites in parish burial grounds, a right given by the Burial Laws Amendment Act 1880 that had up to then been ignored by the Anglican clergy. It was this case, which was hailed as a great victory throughout Wales, and his writings in Udgorn Rhyddid that led to his adoption as the Liberal candidate for Carnarvon Boroughs on 27 December 1888.

In 1889 he became an Alderman on the Carnarvonshire County Council which had been created by the Local Government Act 1888. At that time he appeared to be trying to create a separate Welsh national party modelled on Parnell's Irish Parliamentary Party and worked towards a union of the North and South Wales Liberal Federations. For the same county Lloyd George would also become a JP (1910) and chairman of Quarter Sessions (1929–38), and DL in 1921.

Lloyd George was returned as Liberal MP for Carnarvon Boroughs – by a margin of 19 votes – on 13 April 1890 at a by-election caused by the death of the former Conservative member. He sat with an informal grouping of Welsh Liberal members with a programme of disestablishing and disendowing the Church of England in Wales, temperance reform, and Welsh home rule. He would remain an MP until 1945, 55 years later.

He was soon speaking on Liberal issues (particularly temperance – the "local option" – and national as opposed to denominational education) throughout England as well as Wales. During the next decade, Lloyd George campaigned in Parliament largely on Welsh issues and in particular for disestablishment and disendowment of the Church of England. He wrote extensively for Liberal papers such as the Manchester Guardian. When Gladstone retired in 1894 after the defeat of the second Home Rule Bill, the Welsh Liberal members chose him to serve on a deputation to william Harcourt to press for specific assurances on Welsh issues; when those were not provided, they resolved to take independent action if the government did not bring a bill for disestablishment. When that was not forthcoming, he and three other Welsh Liberals (David Alfred Thomas, Herbert Lewis and Frank Edwards) refused the whip on 14 April 1894 but accepted Lord Rosebery's assurance and rejoined the official Liberals on 29 May. Thereafter, he devoted much time to setting up branches of Cymru Fydd (Young Wales), which, he said, would in time become a force like the Irish National Party. He abandoned this idea after being criticised in Welsh newspapers for bringing about the defeat of the Liberal Party in the 1895 election and when, at a meeting in Newport on 16 January 1896, the South Wales Liberal Federation, led by David Alfred Thomas and Robert Bird moved that he be not heard.

As backbench members of the House of Commons were not paid at that time, he supported himself and his growing family by continuing to practise as a solicitor, opening an office in London under the name of Lloyd George and Co. and continuing in partnership with william George in Criccieth. In 1897 he merged his growing London practice with that of Arthur Rhys Roberts (who was to become Official Solicitor) under the name of Lloyd George, Roberts and Co..

Lloyd George had been impressed by his journey to Canada in 1899. Although sometimes wrongly supposed – both at the time and subsequently – to be a Little Englander, he was not an opponent of the British Empire per se, but in a speech at Birkenhead (21 November 1901) he stressed that it needed to be based on freedom, including for India, not "racial arrogance". Consequently, he gained national fame by displaying vehement opposition to the Second Boer War. Following Rosebery's lead, he based his attack firstly on what were supposed to be war aims – remedying the grievances of the Uitlanders and in particular the claim that they were wrongly denied the right to vote, saying "I do not believe the war has any connection with the franchise. It is a question of 45% dividends" and that England (which did not then have universal male suffrage) was more in need of franchise reform than the Boer republics. A second attack came on the cost of the war, which, he argued, prevented overdue social reform in England, such as old age pensions and workmen's cottages. As the fighting continued, his attacks moved to its conduct by the generals, who, he said (basing his words on reports by william Burdett-Coutts in The Times), were not providing for the sick or wounded Soldiers and were starving Boer women and children in concentration camps. But his major thrusts were reserved for the Chamberlains, accusing them of war profiteering through the family company Kynoch Ltd, of which Chamberlain's brother was Chairman. The firm had won tenders to the War Office though its prices were higher than some of its competitors. After speaking at a meeting in Birmingham, Lloyd George had to be smuggled out disguised as a policeman, as his life was in danger from the mob. At this time the Liberal Party was badly split as H. H. Asquith, R. B. Haldane and others were supporters of the war and formed the Liberal Imperial League. On the day Edward VII was signing the Entente Cordiale with France, Rosebery warned Lloyd George that it would increase the likelihood of a war with Germany. He tried in vain to persuade Rosebery to become Liberal leader again.

Lloyd George was the spokesman for the Nonconformists, and they made a major issue out of the government's Education Act 1902. It provided local funding for Church of England schools, which represented the religious enemy. The bill passed but opposition to it helped reunite the Liberals. His successful amendment that the county need only fund those schools where the buildings were in good repair served to make the Act a dead letter in Wales, where the counties were able to show that most Church of England schools were in poor repair. Having already gained national recognition for his anti-Boer War campaigns, his leadership of the attacks on the Education Act gave him a strong parliamentary reputation and marked him as a likely Future cabinet member.

In 1905, Lloyd George entered the new Liberal Cabinet of Sir Henry Campbell-Bannerman as President of the Board of Trade. In that position he introduced legislation on many topics, from merchant shipping and the Port of London to companies and railway regulation. His main achievement was in stopping a proposed national strike of the railway unions by brokering an agreement between the unions and the railway companies. While almost all the companies refused to recognise the unions, Lloyd George persuaded the companies to recognise elected representatives of the workers who sat with the company representatives on conciliation boards—one for each company. If those boards failed to agree then there was a central board.

George Riddell, 1st Baron Riddell, a wealthy newspaper publisher, was a close confidant and financial angel of Lloyd George from 1908 to 1922, and Riddell's highly perceptive and revealing diary has made him "Lloyd George's Boswell". During Lloyd George's first year as prime minister, in summer 1917, Riddell assessed his personality:

Under his leadership after 1909, Liberals extended minimum wages to farm workers.

Lloyd George had a considerable reputation as a womaniser, which led to his being nicknamed "the Goat" (coined by Sir Robert Chalmers, Permanent Secretary to the Treasury from 1911). Kitchener is said to have remarked early in the First World War that he tried to avoid sharing military secrets with the Cabinet, as they would all tell their wives, apart from Lloyd George "who would tell someone else's wife".

In 1913, Lloyd George, along with Rufus Isaacs, the Attorney General, was involved in the Marconi scandal. Accused of speculating in Marconi shares on the inside information that they were about to be awarded a key government contract (which would have caused them to increase in value), he told the House of Commons that he had not speculated in the shares of "that company", which was not the whole truth as he had in fact speculated in shares of Marconi's American sister company. This scandal, which would have destroyed his career if the whole truth had come out at the time, was a precursor to the whiff of corruption (e.g. the sale of honours in 1922) that later surrounded Lloyd George's premiership.

Lloyd George remained in office as Chancellor of the Exchequer for the first year of the Great War. The budget of 17 November 1914 had to allow for lower taxation receipts because of the reduction in world trade. The Crimean and Boer Wars had largely been paid for out of taxation; but Lloyd George raised debt financing of £321 million. Huge increases in Supertax and income tax rates were not followed by sales and purchase tax revenue rises. While raising £63 million more, the budget was distinguished by the crude attempt to eradicate drinking during wartime, known as the King's Pledge.

Late in 1915 Lloyd George became a strong supporter of general conscription, an issue that divided principled Liberals, but helped the passage of several conscription acts from January 1916 onwards. In spring 1916, Milner hoped Lloyd George could be persuaded to bring down the coalition government by resigning, but this did not happen.

The armed insurrection by Irish republican freedom fighters, known as the Easter Rising, took place in Dublin during Easter Week, 1916. The government responded with harsh repression; key Leaders were quickly executed. The Catholic Irish then underwent a dramatic change of mood, and shifted to demand vengeance and independence. In 1917 Lloyd George called the 1917–18 Irish Convention in an attempt to settle the outstanding Home Rule for Ireland issue. However, the upsurge in republican sympathies in Ireland following the Easter Rising coupled with Lloyd George's disastrous attempt to extend conscription to Ireland in April 1918 led to the wipeout of the Irish Parliamentary Party at the December 1918 election. Replaced by Sinn Féin MPs, they immediately declared an Irish Republic.

The Corn Production Act 1917 bestowed upon the Board of Agriculture the power to ensure that all land was properly cultivated, appointed a wages board to operate a new minimum wage in agriculture, and guaranteed minimum prices for wheat and oats.

The Representation of the People Act 1918 greatly extended the franchise for men (by abolishing most property qualifications) and gave the vote to many women over 30, and the Parliament (Qualification of Women) Act 1918 enabled women to sit in the House of Commons. The Sex Disqualification (Removal) Act 1919 provided that "A person shall not be disqualified by sex or marriage from the exercise of any public function, or from being appointed to or holding any civil or judicial office or post, or from entering or assuming or carrying on any civil profession or vocation, or for admission to any incorporated society...". The Rent Act 1920 safeguarded working-class tenants against exorbitant rent increases. Rent controls were continued after the war, and an "out-of-work donation" was introduced for ex-servicemen and civilians.

The War Cabinet was formally maintained for much of 1919, but as Lloyd George was out of the country for many months this made little difference. In October 1919 a formal Cabinet was reinstated.

Throughout the 1920s Lloyd George remained highly visible in politics; predictions that he would return to power were Common, but it never happened. He still controlled a large fund (thought to have been between £1m and £3m, or £50m–£150m at 2015 prices) from his Investments in newspaper ownership and from his sale of titles.

In May 1920 a Soviet trade delegation led by Leonid Krasin visited Britain, and on its second visit in August it was accompanied by Lev Kamenev, a leading member of the Soviet regime. Coming so soon after the Russian Revolution and against the backdrop of the Battle of Warsaw in summer 1920, this was of deep concern to Field Marshal Wilson, the Chief of the Imperial General Staff, who thought Lloyd George "a traitor & a Bolshevist". The Anglo-Soviet Trade Agreement was signed on 16 March 1921. The more traditional wing of the Unionist Party had no intention of introducing reforms, which led to three years of frustrated fighting within the coalition both between the National Liberals and the Unionists and between factions within the Conservatives themselves. Many Conservatives were angered by the granting of independence to the Irish Free State and by Montagu's moves towards limited self-government for India, while a sharp economic downturn and wave of strikes in 1921 damaged Lloyd George's credibility. In June 1922 Conservatives were able to show that he had been selling knighthoods and peerages – and the Order of the British Empire which was created in 1917 – for money. Conservatives were concerned by his Desire to create a party from these funds comprising moderate Liberals and themselves.

The coalition was dealt its final blow on 19 October 1922. After criticism of Lloyd George over his threat of war with Turkey over the Chanak Crisis, the Conservative leader, Austen Chamberlain, summoned a meeting of Conservative Members of Parliament at the Carlton Club to discuss their attitude to the Coalition in the forthcoming election. Chamberlain and other Conservatives such as Arthur Balfour argued for supporting Lloyd George, while former party leader Bonar Law argued the other way, claiming that breaking up the coalition "wouldn't break Lloyd George's heart". The main attack came from Stanley Baldwin, then President of the Board of Trade, who spoke of Lloyd George as a "dynamic force" who would break the Conservative Party. Baldwin and many of the more progressive members, like Austen Chamberlain, of the Conservative Party, and those who fundamentally opposed Lloyd George split. They sealed Lloyd George's fate with a vote of 187 to 87 in favour of the motion "That this meeting of Conservative members of the House of Commons declares its opinion that the Conservative Party, whilst willing to cooperate with Coalition Liberals, fights the election as an independent party, with its own leader and its own programme." Chamberlain resigned the same day.

Lloyd George was consistently pro-German after 1923. He supported German demands for territorial concessions and recognition of its "great power" status; he paid much less attention to the security concerns of France, Poland, Czechoslovakia and Belgium. In August 1934 (following Austria's transition to fascism), he insisted Germany could not wage war, and assured European nations that there would be no risk of war during the next ten years. In September 1936, he went to Germany to talk with Hitler. Hitler said he was pleased to have met "the man who won the war"; Lloyd George was moved, and called Hitler "the greatest living German". Lloyd George also visited Germany's public works programmes and was impressed. On his return to Britain, he wrote an article for The Daily Express praising Hitler, stating: "The Germans have definitely made up their minds never to quarrel with us again." He believed Hitler was "the George Washington of Germany"; that he was rearming Germany for defence and not for offensive war; that a war between Germany and the Soviet Union would not happen for at least ten years; that Hitler admired the British and wanted their friendship but that there was no British leadership to exploit this. However, by 1937, Lloyd George's distaste for Neville Chamberlain led him to disavow Chamberlain's appeasement policies.

The disastrous election result in 1924 left the Liberals as a weak third party in British politics, with just over 40 MPs. Although Asquith, who had again lost his seat and was created an Earl, remained Liberal leader, Lloyd George was elected chairman of the Liberal MPs by 26 votes to 7. Sir John Simon and his followers were still loyal to Asquith (after 1931 Simon would lead a breakaway National Liberal Party, which eventually merged with the Conservatives) whilst Walter Runciman led a separate radical group within the Parliamentary Party.

Lloyd George was now mainly interested in the reform of land ownership, but had only been permitted to put a brief paragraph about it in the hastily drafted 1924 Liberal manifesto. In the autumn of 1925, despite the hostility of Hobhouse, Runciman and Alfred Mond, he began an independent campaign, soon to become “The Land and the Nation” (the "Green Book", first of a series of policy pamphlets produced by Lloyd George in the late 1920s). Asquith rebuked him, but was ignored, and they reached an agreement in principle on 2 December, then together they presented Lloyd George's plans to the National Liberal Federation on 26 February 1926.

As Liberal leader at last, Lloyd George used his fund to Finance candidates and put forward innovative ideas for public works to reduce unemployment (as detailed in pamphlets such as the "Yellow Book" and the "Orange Book"). Lloyd George was also helped by John Maynard Keynes to write We can Conquer Unemployment, setting out economic policies to solve unemployment. In 1927 the party faced historic charges of corruption first raised during Rosebery's period of ineffectual party management in the 1890s. In 1927 Lloyd George gave £300,000 plus an annual grant of between £30,000 and £40,000 for the operations of the Liberal headquarters. He also gave £2,000 per annum to the parliamentary party until 1931. Even with the money the results at the 1929 general election were disappointing. The Liberals increased their support only to 60 or so seats, while Labour became the largest party for the first time. Once again, the Liberals ended up supporting a minority Labour government. In 1929 Lloyd George became Father of the House (longest-serving member of the Commons), an honorific position without power.

In 1931 an illness prevented his joining the National Government when it was formed. Later when the National Government called a General Election he tried to pull the Liberal Party out of it but succeeded in taking only a few followers, most of whom were related to him; the main Liberal Party remained in the coalition for a year longer, under the leadership of Sir Herbert Samuel. By the 1930s Lloyd George was on the margins of British politics, although still intermittently in the public eye and publishing his War Memoirs. Lloyd George was President of the London Welsh Trust, which runs the London Welsh Centre, Gray's Inn Road, from 1934 until 1935.

In January 1935 Lloyd George announced a programme of economic reform, called "Lloyd George's New Deal" after the American New Deal. This Keynesian economic programme was essentially the same as that of 1929. MacDonald requested that he put his case before the Cabinet, and so in March Lloyd George submitted a 100-page memorandum that was cross-examined between April and June in ten meetings of the Cabinet's sub-committee. However, the programme did not find favour; two-thirds of Conservative MPs were against Lloyd George's joining the National government, and some Cabinet members would have resigned if he had joined.

In the last important parliamentary intervention of his career, which occurred during the crucial Norway Debate of May 1940, Lloyd George made a powerful speech that helped to undermine Chamberlain as Prime Minister and to pave the way for the ascendancy of Churchill. Churchill offered Lloyd George the agriculture portfolio in his Cabinet but he refused, citing his unwillingness to sit alongside Chamberlain. Lloyd George also thought that Britain's chances in the war were dim, and he remarked to his secretary: "I shall wait until Winston is bust." He wrote to the Duke of Bedford in September 1940 advocating a negotiated peace with Germany after the Battle of Britain.

He had five children by his first wife, Margaret: Richard (1889–1968), Mair (1890–1907, who died during an appendectomy), Olwen (1892–1990), Gwilym (1894–1967) and Megan (1902–1966). He remained married to Margaret, and remained fond of her until her death on 20 January 1941; Lloyd George was deeply upset by the fact that bad weather prevented him from being with her when she died.

In October 1943, aged 80, and to the disapproval of his children, he married his secretary and mistress, Frances Stevenson. He had first met Stevenson in 1910, and she had worked for him first as a Teacher for Megan in 1911; their affair began in early 1913. Lloyd George may well have been the father of Stevenson's daughter Jennifer (1929–2012), born long before they wed.

Although he had displayed political courage all his life, in his last years he gave way to physical timidity and hypochondria. He continued to attend Castle Street Baptist Chapel in London, and to preside over the national eisteddfod at its Thursday session each summer. In September 1944, he and Frances left Churt for Tŷ Newydd, a farm near his boyhood home in Llanystumdwy. He was now weakening rapidly and his voice failing. He was still an MP but had learned that wartime changes in the constituency meant that Carnarvon Boroughs might go Conservative at the next election. On New Years Day 1945, Lloyd George was raised to the peerage as Earl Lloyd-George of Dwyfor, and Viscount Gwynedd, of Dwyfor in the County of Caernarvonshire.

His son, Gwilym, and his daughter, Megan, both followed him into politics, and were elected members of parliament. They were politically faithful to their father throughout his life, but after 1945 each drifted away from the Liberal Party, Gwilym finishing his career as a Conservative Home Secretary and Megan becoming a Labour MP in 1957, perhaps symbolising the fate of much of the old Liberal Party.

A great boulder marks his grave; there is no inscription. However a monument designed by the Architect Sir Clough Williams-Ellis was subsequently erected around the grave, bearing an englyn (strict-metre stanza) engraved on slate in his memory composed by his nephew Dr william George. Nearby stands the Lloyd George Museum, also designed by Williams-Ellis and opened in 1963.

He was voted the third greatest British prime minister of the 20th century in a poll of 139 academics organised by MORI, and in 2002 he was named among the 100 Greatest Britons following a UK-wide vote.

The Battle of Passchendaele began on 31 July, but soon became bogged down in unseasonably early wet weather, which turned much of the battlefield into barely passable swamp in which men and animals sometimes drowned, whilst the mud and rain severely reduced the accuracy and effectiveness of artillery, the dominant weapon of the time. Lloyd George tried to enlist the King for diverting efforts against Austria-Hungary, telling Stamfordham (14 August) that the King and Prime Minister were "joint trustees of the nation" who had to avoid waste of manpower. A new Italian offensive began (18 August), but Robertson advised that it was "false strategy" to call off Passchendaele to send reinforcements to Italy, and despite being summoned to George Riddell's home in Sussex, where he was served apple pudding (his favourite dish), agreed only reluctantly. The Anglo-French leadership agreed in early September to send 100 heavy guns to Italy (50 of them French) rather than the 300 which Lloyd George wanted – Lloyd George talked of ordering a halt to Passchendaele, but in Hankey's words "funked it" (4 September). Had he not done so his government might have fallen, for as soon as the guns reached Italy Cadorna called off his offensive (21 September).

Lloyd George represented Britain at the Versailles Peace Conference, clashing with the French Prime Minister, Georges Clemenceau, the US President, Woodrow Wilson, and the Italian Prime Minister, Vittorio Orlando. Unlike Clemenceau and Orlando, Lloyd George on the whole stood on the side of generosity and moderation. He did not want to utterly destroy the German economy and political system—as Clemenceau demanded—with massive reparations. The Economist John Maynard Keynes looked askance at Lloyd George's economic credentials in The Economic Consequences of the Peace, calling the Prime Minister a "goat-footed bard, half-human visitor to our age from the hag-ridden magic and enchanted woods of Celtic antiquity".

The Liberal Shadow Cabinet, including Lloyd George, unequivocally backed Baldwin's handling of the General Strike on 3 May, but Lloyd George then wrote an article for the American press more sympathetic to the strikers, and did not attend the Shadow Cabinet on 10 May, sending his apologies on “policy grounds”. Asquith sent him a public letter (20 May) rebuking him for not attending the meeting to discuss his opinions with colleagues in private. Lloyd George’s letter of 10 May had not been published, making it appear that Asquith had fired the first shot, and Lloyd George sent a public reply, moderate in tone (the Journalist C. P. Scott helped him draft it), on 25 May. In late May, the executive of the National Liberal Federation convened to plan the agenda for the following month's conference. 16 were pro Asquith and 8 pro Lloyd George; they planned a motion expressing confidence in Asquith, but another option was also proposed to seek Asquith’s opinion first, and also general feeling of regret at having been forced to choose between Asquith and Lloyd George. Asquith then wrote another public letter (1 June) stating that he regarded Lloyd George’s behaviour as tantamount to resignation, the same as if a Cabinet Minister had refused to abide by the principle of collective responsibility. Twelve leading Liberals wrote in Asquith’s support to “The Times” (1 June). However, Lloyd George had more support in the wider party than among the grandees: the London Liberal Candidates’ Association (3 June) defied its officers and expressed its dismay at the split, effectively supporting Lloyd George, and on 8 June the Liberal MPs voted 20:10 urging a reconciliation. Asquith had planned to launch a fightback at the National Liberal Federation in Weston-Super-Mare, but on 12 June, five days before the conference was due to start, he suffered a stroke which put him out of action for three months. Lloyd George was given a rapturous welcome. Asquith resigned as party leader in October, dying in 1928.