Caitríona O'Reilly was born in Dublin in 1973, grew up in Wicklow, and studied English and Archeology at Trinity College, Dublin. She wrote her Ph.D. on American poetry, specifically Emily Dickinson, H.D., and Sylvia Plath. She has taught at Trinity College, Dublin, St. Patrick's College, Dublin, and the Dun Laoghaire Institute of Arts and Design.
O'Reilly is on the editorial board of the journal Metre, for which she has written reviews and essays. She has also reviewed for The Irish Times, Poetry Review, and Times Literary Supplement, among others.
Her first collection, The Nowhere Birds (Bloodaxe Press, 2001) won the Rooney Prize for Irish Literature, and her poetry has been included in many anthologies.
She lives in Wicklow.