Durcan grew up in Dublin and in Turlough, County Mayo. His father, John, was a barrister and circuit court judge; father and son had a difficult and formal relationship. Durcan enjoyed a warmer and more natural relationship with his mother, Sheila MacBride Durcan. He studied law and economics at University College Dublin. While at college, Durcan was kidnapped by his famiily and committed against his will to Saint John of God psychiatric hospital in Dublin, and later to a Harley Street clinic where he was subjected to electric shock treatment and heavy dosages of barbiturates and Mandrax.

Durcan moved to live in London in 1966 where he worked at the North Thames Gas Board. He met Nessa O'Neill in 1968; they married and had two daughters, Sarah and Siabhra. They lived in South Kensington, then moved to Cork where his wife taught in a prison. The marriage ended at the beginning of 1984.

Durcan's main published collections include: A Snail in my Prime, Crazy About Women, Greetings to Our Friends in Brazil and Cries of an Irish Caveman. He appeared on the 1990 Van Morrison album Enlightenment, giving an idiosyncratic vocal performance on the song, "In The Days Before Rock'n'Roll", which he also co-wrote.

In 2003, he published a collection of his weekly addresses to the nation, Paul Durcan's Diary, on RTÉ Radio I program Today with Pat Kenny.

He is a member of Aosdána.

In 2009, he was conferred with an honorary degree by Trinity College, Dublin.