Kinsella spends most of his childhood in the Kilmainham/Inchicore area of Dublin. He is educated at the Model School, Inchicore, where classes are taught in Irish Gaelic, and at the O’Connell School in North Richmond Street, Dublin. He acquires a series of grants and scholarships that allow him to attend University College Dublin, where he studies physics and chemistry before receiving a degree in public administration.
Kinsella begins serving in the Irish civil service in 1946, and in the early 1950s he meets Liam Miller, the founder of Dolman Press, which publishes much of Kinsella’s poetry beginning in 1952. Among these publications are Poems (1956), his first volume of collected work, Another September (1958), which contains poems that explore the imposition of existential order through various forms, be they natural or products of the poet’s imagination and Downstream (1962), a collection focusing on war and political and social disruption in modern Ireland.
In 1965 Kinsella leaves the Irish civil service and takes a position as a writer in residence at Southern Illinois University in Carbondale (1965–70). During this time he publishes Nightwalker, and Other Poems (1967), a sombre collection ruminating on Ireland’s past and turbulent present. His translation of the ancient Gaelic saga The Cattle Raid of Cooley (Táin bó Cuailnge) is published in 1969, and the following year he begins teaching at Temple University in Philadelphia. New Poems 1956–73 (1973) and One, and Other Poems (1979) skillfully extend the themes of love, death, and rejuvenation.
Kinsella founds his own publishing company, the Peppercanister Press, in Dublin in 1972, which allows him to publish pamphlets and individual poems in limited editions without relying on submissions to journals or magazines. His first poem to be published through his press is Butcher’s Dozen (1972), about Bloody Sunday, in which 13 demonstrators are killed by British troops in Derry, Northern Ireland, and the ensuing tribunal. Blood & Family (1988) combines four short collections of prose and verse originally published individually through Peppercanister, and Godhead (1999) explores the Trinity in the light of contemporary society. Later works published through Peppercanister include Marginal Economy (2006), Man of War (2007), and Belief and Unbelief (2007). Numerous collections of his poems have been released, including Collected Poems, 1956–2001 (2001) and Selected Poems (2007).
In December 2018, Kinsella is awarded Doctor in Littoris, Honoris Causa, by Trinity College Dublin.