Johnson was born in Chapelton, a small town in the rural parish of Clarendon, Jamaica. In 1963 he came to live in Brixton, London, joining his mother who had emigrated to Britain shortly before Jamaican independence in 1962. Johnson attended Tulse Hill School in Lambeth. While still at school he joined the British Black Panther Movement, helped to organise a poetry workshop within the movement, and developed his work with Rasta Love, a group of poets and drummers.
Johnson went on to study for a degree in sociology at Goldsmiths College in New Cross, London (graduating in 1973), which currently holds his personal papers in its archives. During the early to mid-1970s he was employed as the first paid library resources and education officer at the Keskidee Centre, where his poem Voices of the living and the dead was staged, produced by Jamaica novelist Lindsay Barrett, with music by the reggae group Rasta Love. Johnson has recalled: "it was fantastic, you know, having written something and having it staged with actors and musicians. That was back in 1973 before I had a poem published anywhere. That was before anyone had ever heard of Linton Kwesi Johnson."
Johnson received a C. Day-Lewis Fellowship in 1977, and that year became writer-in-residence for the London Borough of Lambeth. He was made an Associate Fellow of Warwick University in 1985 and an Honorary Fellow of Wolverhampton Polytechnic in 1987, and in 1990 received an award at the XIII Premio Internazionale Ultimo Novecento from the city of Pisa for his contribution to poetry and popular music. In 1998 he was awarded the Premio Piero Ciampi Citta di Livorno Concorso Musicale Nazionale in Italy.
In 2003 Johnson was bestowed with an honorary fellowship from his alma mater, Goldsmiths College, University of London. In 2004 he became an Honorary Visiting Professor of Middlesex University in London. In 2005 he was awarded a silver Musgrave Medal from the Institute of Jamaica for distinguished eminence in the field of poetry. In 2012, he was awarded the Golden PEN Award by English PEN for "a Lifetime's Distinguished Service to Literature".
He is a Trustee of the George Padmore Institute.
In August 2014 it was announced that he would receive the Order of Distinction in October that year.
On 20 April 2017 he was awarded an Honorary Doctorate of Literature (D.Litt) by Rhodes University in South Africa.
Most of Johnson's poetry is political, dealing mainly with the experiences of being an African-Caribbean in Britain: "Writing was a political act and poetry was a cultural weapon...", he told an interviewer in 2008. However, he has also written about other issues, such as British foreign policy and the death of anti-racist marcher Blair Peach. Johnson wrote "Reggae fi Dada" on the death of his father in 1982, blaming social conditions. His most celebrated poems were written during the government of Prime Minister Margaret Thatcher. The poems contain graphic accounts of the racist police brutality occurring at the time (cf. "Sonny's Lettah"). Johnson's poetry makes clever use of the unstandardised transcription of Jamaican patois.
Johnson's poems first appeared in the journal Race Today, which published his first collection of poetry, Voices of the Living and the Dead, in 1974. Dread Beat An' Blood, his second collection, was published in 1975 by Bogle-L'Ouverture.
A collection of his poems has been published as Mi Revalueshanary Fren by Penguin Modern Classics. Johnson is one of only three poets to be published by Penguin Modern Classics while still alive.
Johnson wrote for New Musical Express, Melody Maker, and Black Music in the 1970s, and while working on a freelance basis for Virgin Records during this period he wrote biographies for reggae artists on the label, as well as sleeve notes and copy for adverts.
Johnson's best-known albums include his debut Dread Beat an' Blood (1978), Forces of Victory (1979), Bass Culture (1980), LKJ in Dub (1980), and Making History (1983). Across them are spread classics of the dub poetry school of performance – and, indeed, of reggae itself – such as "Dread Beat An' Blood", "Sonny's Lettah", "Inglan Is A Bitch", "Independent Intavenshan" and "All Wi Doin Is Defendin". His poem Di Great Insohreckshan is his response to the 1981 Brixton riots. The work was the subject of a BBC Radio 4 program in 2007.
Johnson's work, allied to the Jamaican "toasting" tradition, is regarded as an essential precursor of rap.
Johnson's record label LKJ Records, launched in 1981, is home to other reggae artists, some of whom made up the Dub Band, with whom Johnson mostly recorded, and other dub poets, such as Jean "Binta" Breeze. Past releases on the label include recordings by Mikey Smith.Dread Beat an' Blood – Virgin, 1978 (as Poet And The Roots).
Forces of Victory – Island, 1979.
Bass Culture – Island, 1980.
The Best of Linton Kwesi Johnson – Epic, 1980 (compilation).
LKJ in Dub – Island, 1980.
Making History – Island, 1983.
Reggae Greats – Mango, 1984 (compilation).
LKJ Live in Concert with the Dub Band – LKJ Records, 1985.
Dub Poetry – Mango, 1985 (Compilation).
Tings An' Times – LKJ Records, 1991.
LKJ in Dub: Volume 2 – LKJ Records, 1992.
LKJ Presents – LKJ Records, 1996.
A Cappella Live – LKJ Records, 1996.
Independent Intavenshan – Island, 1998 (compilation).
More Time – LKJ Records, 1999.
LKJ in Dub: Volume 3 – LKJ Records, 2002.
Straight to Inglan's Head – Universal, 2003 (compilation).
Live in Paris – Wrasse, 2004.