O'Brien began publishing poetry and criticism in the 1960s. He has been a contributor to "Artforum", "Film Comment", "The New York Times" and "The New York Times Book Review", "Village Voice", "New Republic", "Bookforum", and, especially, to the "New York Review of Books". He has also been published in numerous other publications, including "Filmmaker", "American Heritage", "The Armchair Detective", "Bomb", "Boston Globe", "Fence", GQ, "The Los Angeles Times Book Review", "Men’s Vogue", "Mother Jones", "The Nation", "Newsday", and Slate, and has contributed many essays for liner notes for The Criterion Collection. In addition, his work has been included in numerous anthologies.