Herbert was born at Ashtead Lodge, Ashtead, Surrey on 24 September 1890. His father, Patrick Herbert Coghlan Herbert (1849-1915), was a civil servant (assistant secretary of the Judicial and Public Department) in the India Office, of Irish origin, and his mother, Beatrice Eugenie (née Selwyn), was the daughter of Sir Charles Jasper Selwyn, a Lord Justice of Appeal. He had two younger brothers, both of whom died in battle- Owen william Eugene, 2nd Lieutenant, Royal Field Artillery, killed at Mons in 1914, and Sidney Jasper, Captain R.N., killed 1941 aboard the H.M.S. Hood. His mother died of tuberculosis when he was eight years old, shortly before he left to attend The Grange in Folkestone, a preparatory school.

Starting in 1910, he contributed regularly to Punch. One series of his it took was Misleading Cases in the Common Law – the work for which he is best remembered. These were satirical pieces in the form of "law reports" or "judgements" on various aspects of the English legal and judicial system. Many featured the exploits of Albert Haddock, a tireless and veteran litigant. One of the best-known and most colourful is Board of Inland Revenue v Haddock, also known as "The Negotiable Cow". Even the title is a humorous allusion to the entirely serious "Smith's Leading Cases". Herbert often referred to himself as "A. P. Haddock" in skits in Punch magazine, whether or not these had a courtroom setting.

In the summer of 1914, Herbert first met his Future wife, Gwendolyn Harriet Quilter, the daughter of Harry Quilter. They became engaged in December 1914 and were married in the first week of 1915 by Frederic Iremonger, the vicar of St James the Great in Bethnal Green. Herbert wore his formal dress uniform of an Acting Leading Seaman during the wedding. They spent their honeymoon in a room in Fulham Road. Gwendolyn lived to the age of 97, dying in 1986. Lady Herbert was elected as the first President of Hammersmith Chess Club in 1966 and was a well-known face on the chess circuit at that time. They had four children Crystal, Lavender, Jocelyn and John.

"C" and "D" companies of Hawke Battalion departed for Gallipoli in early 1915, briefly stopping in Malta before arriving at the Moudros on 17 May. The battalion finally arrived at Gallipoli on 27 May. Herbert was put in command of No. 11 Platoon, "C" Company, which was composed mostly of Tynesiders and also two men from a remote Durham mining town. A week after arrival, the battalion suffered heavy casualties at the Third Battle of Krithia. In July 1915, Herbert went down with an illness and had to spend time recovering in a military hospital. When he was passed "fit for light duty", he was seconded to the Naval Intelligence Division at Whitehall. It was at this time that he decided to begin renting 12 Hammersmith Terrace.

During the pre-war period, Herbert drafted a number of bills that were printed on the Order Paper, including a Betting and Bookmakers Bill, a Public Refreshment Bill and a Spring (Arrangements) Bill, which was written in verse. Herbert made numerous attacks on the Entertainments Duty, which had been introduced as a "temporary, war-time tax" in 1916. In his campaign against the duty, Herbert worked closely with william Mabane, and they made some headway when in 1939 the Chancellor of the Exchequer Sir John Simon reduced the duty. Herbert also spoke out against the proposed Population (Statistics) Bill in 1937, making a speech that was received with "loud laughter" in the Commons chamber, making it, according to Punch, "an astonishing occasion". Herbert and others brought in several amendments to the bill before it reached the statute book in 1938.

On medical leave back in England following the injury, Herbert began writing his first book, The Secret Battle, which was finished "in a few weeks". He was also elected a member of the Savage Club, and was raised by Punch to the "exclusive group of its contributors who were allowed to attach their initials to their work." On 2 October 1918, Herbert sailed out of Liverpool in a convoy bound for Alexandria. His role was as assistant to the Commodore. After arriving at Port Said, he was given a free pass to Cairo and was allowed to make a number of unaccompanied incursions inland. He was able to visit a number of places on the North African coast, and from Tunis, he took a train to Constantine, and then to Algiers. On 11 November, he went by train from Oran to Tlemcen. Exactly at 11 am, he heard that the Armistice had been signed. He wrote that "I must have been the only Englishman for at least 80 miles."

Herbert was called to the Bar by Inner Temple in 1919 and entered the chambers of Leslie Scott. He was joined by two of his Oxford friends, Walter Monckton and Henry Strauss, who were called on the same day. Although he spent some time at Inner Temple, he never practised law and did not enter a legal career. He later declared himself "forever sorry" that he was "not of the proud and faithful brotherhood who serve the laws of England."

Unable to sustain himself on Punch's "eccentric rates of payment", Herbert wrote his second book, The House by the River, in two months, and it was published in 1920. He handed his literary Business to A. P. Watt, who sold the American rights to The House by the River and also published a collection of his prose submissions to Punch under the title Light Articles Only.

In January 1924, Owen Seaman, the Editor of Punch, invited Herbert to join their staff. Herbert accepted and his accession to the staff meant he would receive a salary of £50 a week. In 1925, Herbert attended the Third Imperial Press Conference on behalf of Punch, where he made his first speech in front of a large audience in Melbourne, where it was described as "delectably witty" by Sir Harry Brittain.

In 1926, Herbert was invited by Nigel Playfair to write "an entertainment" for the Lyric Theatre, Hammersmith. The result was Riverside Nights, performed at the Lyric in April 1926. His next play, The White Witch, was performed at Haymarket Theatre in September 1926.

Herbert wrote eight novels, including The Water Gipsies (1930), and 15 plays, including the light operas Tantivy Towers (1931) and Big Ben (1946), and the comedy Bless the Bride (1947), which ran for two-and-a-quarter years in London.

Herbert first encountered Parliament in 1934, when he brought the Kitchen Committee of the House of Commons to court for selling liquor without a licence. Hewart, LCJ, ruled that the court would not hear the complaint because the matter fell within parliamentary privilege. Since the decision was never challenged in a higher court, this has led to the unique situation where there has been uncertainty as to "the extent to which statute law applies to either House of Parliament." When, the next year, Herbert published Uncommon Law, Hewart contributed a generous introduction.

In addition to his fiction, Herbert wrote What a Word! in 1935, continuing his campaign in Punch for better use of English, including a section on "Plain English", more than a decade ahead of Sir Ernest Gowers's more celebrated work. Characteristically, Herbert uses humour to make his serious points about good writing. He was the author of the lyrics of the patriotic song Song of Liberty, set in 1940 to the music of Edward Elgar's Pomp and Circumstance March No. 4. After the war he wrote a small booklet called 'The War Story of Southend Pier' detailing an account of when the pier was taken over by the Royal Navy in World War II.

In 1936, Herbert failed to get drawn in the private members' ballot but managed to get the Conservative Rupert De la Bère to sponsor the bill. On 20 November, Herbert made a speech in its favour and it passed its second reading by 78 votes to 12. It was given a third reading in the House of Lords on 19 July 1937 and was passed by 79 votes to 28. It was passed, somewhat strengthened by the House of Lords, in 1938 as the Matrimonial Causes Act 1937. This allowed divorce without requiring proof of adultery, although fake adulteries and the bizarre rules about collusion persisted until the Divorce Reform Act 1969 came into force in 1971.

On 3 November 1938, Herbert enrolled himself and his boat, the Water Gipsy, in the River Emergency Service, which was under the control of the Port of London Authority. Over the summer of 1939, he had taken part in exercises involving simulated air raid and casualty retrieval. In early September 1939, the River Emergency Service reported to their war stations, and Herbert's own crew consisted of Darcy Braddell, vice-president of the Royal Institute of British Architects, Victor Pasmore, Magnus Pyke and John Pudney. At the sounding of the first air raid siren in London in 1939, the Water Gipsy was anchored off Speaker's Steps by Westminster Bridge. A number of MPs left the Commons following the sirens and cheered the Water Gipsy as the only naval vessel in sight, before saluting it.

He was sent to Newfoundland and Labrador in 1943 with Derrick Gunston and Charles Ammon as part of a parliamentary commission to investigate the Future of the dominion. Of the alternatives, he supported independence rather than a confederation.

In autumn 1945, George Orwell had the essay Notes on Nationalism published in the magazine Polemic. In it, he named Herbert as one of the followers of "neo-Toryism", who, according to Orwell, are marked by a "desire not to recognise that British power and influence have declined". Herbert's biographer, Reginald Pound, notes that "APH would have rejected the Tory affiliation, though his inclinations were with the Right."

From July 1945 through to 1946, Herbert worked on the libretto for Charles B. Cochran's new musical, Big Ben. It opened at the Adelphi Theatre on 17 July 1946 and was watched on its opening night by Churchill, Montgomery, Attlee and Herbert, but Cochran was too ill to attend. During its first three months, it took an average of £4,000 a week at the box office, but the running costs were also high so there was no fortune for Cochran or Herbert. The show ended its run at the end of 1946, after 172 performances. Cochran commissioned Herbert to write another musical, Bless the Bride, which opened at the Adelphi on 26 April 1947. It ran for two and a quarter years, and was the source of "an accretion of cash" for Herbert as well as being Cochran's most successful musical.

Herbert sat on the Supreme Court Committee on Practice and Procedures, chaired by Raymond Evershed, which was investigating the cost of litigation. He also chaired the Literary Sub-Committee of the 1948 Summer Olympics in London, which judged the literary compositions of 29 nations in their own languages. He also accepted an invitation to serve on the Council of the Festival of Britain, to be held in 1951. At this time, he was already a member of the Thames Conservancy Board, a trustee of the National Maritime Museum, President of the Inland Waterways Association and a vice President of the Pedestrians' Association for Road Safety. He also authored a critical study of royal commissions for the Institute of Economic Affairs, which was dismissed for its "light touch". Herbert commented that "Had it included graphs and tables and been written in a heavy style it would have been accepted as a major contribution to the practice of sound administration."

Herbert was re-elected in the 1945 general election and continued as an MP until the University seats were abolished in 1950 as a result of the Representation of the People Act 1948. Herbert's last speech, on 23 November 1949, was in favour of the Festival of Britain, a cause he strongly supported. He was knighted in 1945 in Winston Churchill's Resignation Honours. The Times noted "his individual niche in the parliamentary temple as the doughty vindicator of the private member's rights, including not least the right to legislate."

In 1951, Herbert published a memoir of his Service in the House of Commons, Independent Member (Garden City, New York: Doubleday & Co., Inc., 1951).

In his 1957 article "Over Seventy", lamenting the decline of the humorist, P. G. Wodehouse wrote: "I want to see an A. P. Herbert on every street corner, an Alex Atkinson in every local."

Herbert was the subject of a This Is Your Life TV programme in 1961 when he was surprised by Eamonn Andrews.

Herbert loved the River Thames. He lived beside it at Hammersmith, West London. He was a Conservator (a member of the Thames Conservancy Board) and a Freeman of the Company of Watermen and Lightermen. In 1966 he wrote The Thames (Weidenfeld & Nicolson) in which he explored the "machinery" of the river in all its aspects.

In 1967, Herbert published Sundials Old and New; or, Fun with the Sun; a book describing in detail his long fascination with, and experiments in sundial Technology. In the book, he describes all manner of sundials, and recounts many of his experiments in designing and building a number of different Models, including a few that could be used to tell your position on the earth as well as the local time.

In 1970 Herbert published A.P.H., His Life and Times, dedicated to My dear wife, for our 56th anniversary.

In the last days of 1970, Herbert was taken to Middlesex Hospital in Fitzrovia, following a seizure that affected his left side and arm. Within six weeks, he was home again, and over many months his physical powers waned. In August 1971, he wrote his last letter to The Times, an appeal for parliamentary good manners in refraining from "witty derision of the literary exertions of Mr Harold Wilson" and of the "marine activities" of Edward Heath. By then, he was describing himself as "a recumbent nuisance." He died on 11 November 1971, and obituaries were published in both The Times and Punch. The Times supplemented their obituary notice with a leading article. They described him as having done "more than any man of his day to add to the gaiety of the nation."

The title of Alexandra Fuller's 2001 memoir Don't Let's Go to the Dogs Tonight: An African Childhood is taken from a Herbert quote, "Don't let's go to the dogs tonight, for Mother will be there."