The oldest of seven children from a working-class background, Paul Mariani was born in New York City in 1940 and grew up there and on Long Island. He earned his bachelor's degree from Manhattan College, a Master's from Colgate University, and a PhD. from the City University of New York. He is the author of seven poetry collections: Epitaphs for the Journey: New, Selected & Revised Poems (Cascade Books, 2012), Deaths & Transfigurations (Paraclete Press, 2005), The Great Wheel (W. W. Norton, 1996), Salvage Operations: New & Selected Poems (W.W. Norton,1990), Prime Mover (Grove Press, 1985), Crossing Cocytus (Grove Press,1982), and Timing Devices (Godine, 1979).

He has published numerous books of prose, including Thirty Days: On Retreat with the Exercises of St. Ignatius (Viking, 2002), and God and the Imagination: On Poets, Poetry, and the Ineffable (University of Georgia Press, 2002). Other books include A Usable Past: Essays, 1973-1983 (1984), William Carlos Williams: The Poet and His Critics (1975), and A Commentary on the Complete Poems of Gerard Manley Hopkins (1970), as well as six biographies: The Whole Harmonium: The Life of Wallace Stevens (Simon & Schuster (April 2016); Gerard Manley Hopkins: A Life (Viking, 2008): The Broken Tower: A Life of Hart Crane (W. W. Norton, 1999); Lost Puritan: A Life of Robert Lowell (1994), all named New York Times Notable Books of the year; Dream Song: The Life of John Berryman (1990); and William Carlos Williams: A New World Naked (1981), which won the New Jersey Writers Award, was short-listed for an American Book Award, and was also named a New York Times Notable Book of the year.

His honors include fellowships from the Guggenheim Foundation, the National Endowment for the Arts, and the National Endowment for the Humanities. He has also been shortlisted for the Tait Award for biography. He was Distinguished University Professor at the University of Massachusetts, Amherst, where he taught from 1968 until 2000, when he was named University Professor of English at Boston College. In 2009 he received the John Ciardi Award for Lifetime Achievement in Poetry. Mariani and his wife, Eileen, have three grown sons and live in western Massachusetts. He is currently working on a memoir of growing up on the mean streets of Manhattan in the 1940s. The Broken Tower, his biography of Hart Crane, was turned into a film, directed by and starring James Franco, and is available on DVD, including a lengthy interview with Franco. He has also contributed to two films--one on John Berryman, and another on Wallace Stevens. He has lectured widely and read his poems, both here in the U.S. and abroad.