David Blunkett was born on 6 June 1947 at Jessop Hospital, Sheffield, South Yorkshire, with improperly developed optic nerves due to a rare genetic disorder. He grew up in an underprivileged family and in 1959, he endured a family tragedy when his father was gravely injured in an industrial accident in which he fell into a vat of boiling water while at work as a foreman for the East Midlands Gas Board, dying a month later. This left the surviving family in poverty, especially since the board refused to pay compensation for two years because his father worked past the retirement age, dying at age 67.

Blunkett was educated at schools for the blind in Sheffield and Shrewsbury. He was never sent for assessment at the School for the Blind in Worcester, and instead attended the Royal National College for the Blind in Hereford. He was apparently told at school that one of his few options in life was to become a lathe operator. Nevertheless, he won a place at the University of Sheffield, where he gained a BA honours degree in Political Theory and Institutions; one of his lecturers was Bernard Crick. He entered local politics on graduation, whilst gaining a Postgraduate Certificate in Education from Huddersfield Holly Bank College of Education. He spent a total of six years going to evening classes and day-release classes to get the qualifications needed to go to university. He worked as a clerk typist between 1967 and 1969 and as a lecturer in industrial relations and politics between 1973 and 1981.

In 1970, at the age of 22, Blunkett became the youngest-ever councillor on Sheffield City Council and in Britain, being elected while a mature student. He served on Sheffield City Council from 1970 to 1988, and was Leader from 1980 to 1987. He also served on South Yorkshire County Council from 1973 to 1977. This was a time of decline for Sheffield's steel industry. The Conservative MP for Sheffield Hallam, Irvine Patnick, coined the phrase "Socialist Republic of South Yorkshire" to describe the left-wing politics of its local government. Sheffield City Council supported the National Union of Mineworkers in their 1984-85 strike, designated Sheffield a "nuclear-free zone", and set up an Anti-Apartheid Working Party. Blunkett became known as the leader of one of Labour's left-wing councils, sometimes described pejoratively as "loony left". Blunkett was one of the faces of the protest over rate-capping in 1985 which saw several Labour councils refuse to set a budget in a protest against Government powers to restrain their spending. He built up support within the Labour Party during his time as the council's leader during the 1980s, and was elected to the Labour Party's National Executive Committee.

Having unsuccessfully fought Sheffield Hallam in February 1974, at the 1987 general election he was elected Member of Parliament (MP) for Sheffield Brightside with a large majority in a safe Labour seat. He became a party spokesman on local government, joined the Shadow cabinet in 1992 as Shadow Health Secretary and became Shadow Education Secretary in 1994.

Blunkett has also co-authored a number of publications including Building from the Bottom (1982), published by the Fabian Society, and Democracy in Crisis (1987), published by Hogarth, which described the battle between local and central government in the Thatcher years. He has also contributed chapters to many books relating to politics and social policy and has also produced research papers with the University of Sheffield. Other publications include "Ladders Out of Poverty" in 2006 and "Mutual Action, Common Purpose" in 2009 (relating to the voluntary sector).

Blunkett was almost immediately faced with September 11 attacks on the USA. He brought in new anti-terrorism measures, including detention without trial of suspect foreign nationals who couldn't be extradited or deported. It caused a backbench rebellion and provoked strong opposition in the House of Lords, and Blunkett made concessions over incitement to religious hatred (later carried through by his successor) and to introduce a "sunset clause". He authorised MI5 to start collecting bulk telephone communications data on which telephone numbers called each other and when, authorised under a little understood general power under the Telecommunications Act 1984 instead of the Regulation of Investigatory Powers Act 2000 which would have brought independent oversight and regulation. This was kept secret until announced by the then Home Secretary in 2015.

Blunkett divorced his wife, by whom he had three sons, in 1990. In 2004 the News of the World revealed a three-year affair with Kimberly Fortier aka Kimberly Quinn, a former publisher of The Spectator, and the disputed parentage of their then two-year-old child. After prolonged press speculation, DNA tests showed that Blunkett was the father. In 2005, The People newspaper launched a cycle of media speculation about Blunkett's alleged relationship with a young woman. The newspaper later apologised, admitting that the story was entirely false.

He was portrayed by Phil Cornwell in The Comic Strip Presents's 1992 film "Red Nose of Courage".

He also published a light hearted dog orientated look back at his life so far, in On a Clear Day, published by Michael O'Mara Books in 1995.

As Secretary of State, Blunkett pursued conservative reforms, ready to take on the teaching unions and determined to ensure basic standards of literacy and numeracy. He was rewarded with extra funding to cut class sizes, and subsequently there has since 1997 been a massive increase in literacy and numeracy, and there are 42,000 more teachers than in 1997, with doubled spending per pupil in frontline schools (and over 100,000 teaching assistants) through to 2010. A key pillar of Blunkett's work as Education Secretary was the introduction of Sure Start, a government programme which provides services for pre-school children and their families. It works to bring together early education, childcare, health and family support. In 2011 the government effectively started the abolition of Sure Start by lifting the ring fence on earmarked funding and cutting back drastically on the funds available.

Blunkett introduced the teaching of citizenship in schools in 1999, arguing that "We want to ensure that there's a basis of traditional knowledge that's available to all children." Citizenship education provides pupils with the knowledge, skills and understanding to become informed citizens, aware of their rights, duties and responsibilities.

At the start of the Labour government's second term in 2001, Blunkett was promoted to Home Secretary, fulfilling an ambition of his. Observers saw him as Future Prime Minister, and a rival to Chancellor of the Exchequer Gordon Brown's hopes to succeed Blair.

Blunkett radically overhauled 'Victorian' sex offences legislation in 2002, which modernised the sex offences laws dramatically in relation to same-sex and related issues by sweeping away the archaic laws governing homosexuality, while tightening protections against rapists, paedophiles and other sex offenders. The act closed a loophole that had allowed those accused of child rape to escape punishment by arguing the act was consensual and a new offence of adult sexual activity with a child, which covers any sex act that takes place between an adult and a child under 16, was introduced. It was supported by all major political parties in the UK.

Blunkett resigned as Home Secretary on 15 December 2004 amidst allegations that he helped fast-track the renewal of a work permit for his ex-lover's nanny. Mr Blunkett had in 2003 introduced for the first time substantial fees for visa and work permits and their renewal. As a consequence, turnaround times were tightened and customer Service targets strengthened.

The satirist Alistair Beaton wrote the television film A Very Social Secretary, for Channel 4, which was screened in October 2005. He was played by Bernard Hill.

In October 2006, David Blunkett's audio diaries were published in his book The Blunkett Tapes: My Life in the Bear Pit. The tapes detail his time as a cabinet minister until the present date, and provide insights into the workings of the Labour cabinet. They were recorded every week, and contain his view of what was happening in Cabinet at the time, alongside contemporary reflections and more recent thoughts on the events.

He was featured on the Channel Five documentary series 'Banged Up' in 2008.

He was interviewed as part of Armando Iannucci's examination of Milton's Paradise Lost, which screened in May 2009. In it Blunkett speculates on how Milton's Service in Oliver Cromwell's government might have affected his beliefs and jokingly quotes the media as saying "He [Blunkett] is no Milton."

He was a key voice in the 'No to AV' campaign in 2010–11 and has spoken out against the Government's proposed boundary changes.

One of his main interests is volunteering and community Service. In 2011 he published a pamphlet calling for a National Volunteer Programme, which received a wide range of support, particularly among third sector organisations. Since then, Blunkett has commenced putting together and becoming a founder of the Future For Youth Foundation, which sought to tackle high levels of unemployment in young people and which concluded its work in the summer of 2015.

In September 2012 he published In Defence of Politics Revisited, where he set out a range of proposals to increase faith in, and improve the working of, democratic politics. Most recently he was awarded status as an Academician of the Academy of Social Sciences. In July 2013, Sheffield University announced Blunkett had become a Visiting Professor in the Department of Politics, in the world's first Centre for the Public Understanding of Politics.

Blunkett's guide dogs – Ruby, Teddy, Offa, Lucy, Sadie and most recently Cosby – became familiar characters in the House of Commons, usually sleeping at his feet on the floor of the chamber, inspiring occasional witty comments from Blunkett and his fellow MPs on both sides of the house. In one memorable incident, Lucy (a black Labrador curly coat retriever cross) vomited during a speech by Conservative member David Willetts. On occasions when Blunkett was guided by (then Prime Minister) Tony Blair the wry comment has been made: "who is guiding whom?" Another time, his (new) guide dog led him to the Conservative Party benches.

In June 2014, he announced he would not be contesting the election in the following year, stating that he had realised he would not be returning to the frontbenches. In his letter he wrote: "it is clear that the leadership of the Party wish to see new faces in Ministerial office and a clear break with the past".

Blunkett was appointed as Professor of Politics in Practice at the University of Sheffield in June 2015. In 2017 he received an Honorary Doctorate for services to government and education from the University of Huddersfield. Blunkett belongs to the Labour Friends of Israel lobby group.

He is a Vice President of the Royal National Institute of Blind People and a vice President of the National Alzheimer’s Society, and has close links with a range of other charities (local to Sheffield and nationally) including those relating to substance abuse and breast cancer, and is a Patron of the Employers Network for Equality & Inclusion (enei). He is also a long-standing Patron of The Micro & Anophthalmic Children's Society – the UK's only charity supporting families of children born without eyes or with underdeveloped eyes. He is also a former Honorary Chair of the Information Systems Security Association (ISSA-UK) Advisory Board and was until March 2015, Chairman of the not-for-profit International Cyber Security Protection Alliance (ICSPA).