Thomas Kilroy has written fifteen plays. They include The Death and Resurrection of Mr.Roche, The Secret Fall of Constance Wilde and The Shape of Metal. He has written a number of adaptations of Chekhov, Ibsen, Pirandello and Wedekind. He was a member of the board of Field Day Theatre for which he wrote two plays, Double Cross and The Madame MacAdam Travelling Theatre.
His one novel, The Big Chapel, was shortlisted for the 1971 Booker Prize and winner of the Guardian Fiction Prize for the same year.

In the 2004 Irish Times Theatre Awards he received a Special Tribute Award for his contribution to theatre. In February 2008 he was presented with the PEN Ireland Cross Award for his contribution to literature.