Glenn O'Brien graduated from Georgetown University, where he majored in English and Anti-War Demonstrations, before attending the graduate film program at Columbia University. He was a student there when he landed a job at Andy Warhol's Interview magazine. Soon he was made the editor and art director of the young publication, which grew tremendously during his tenure. He left to run the New York bureau of Rolling Stone, then headed to Chicago as articles editor of Playboy's alternative skin magazine, Oui. After a year of exile he returned to New York and a gig at High Times magazine, which cured him of the editor bug for a while. He was briefly its editor in chief before becoming the first editor at large in magazine history, a title which meant he was generally difficult to locate. In 1977 he returned to Interview with the column "Glenn O'Brien's BEAT," which appeared there for twelve years, chronicling the punk, new wave, reggae, and funk scenes as well as his thoughts on just about everything else.

In 1976 he formed the band Konelrad, which played the CBGB circuit as the world's first socialist-realist rock band. In 1978 he launched Glenn O'Brien's TV Party on Manhattan Cable TV's public access channel, creating what David Letterman has called "the greatest TV show ever." TV Party is the subject of a documentary that premiered at the Tribeca Film Festival in 2005; the documentary and numerous episodes are now available on DVD. In 1981 he wrote and produced the film Downtown 81, starring Jean-Michel Basquiat and a host of New York's most interesting musicians. In the early '80s he worked as a stand-up comic and the regular opening act of Buster Poindexter. During these years his writing appeared in publications such as Artforum and Spin, where he worked as "tri-state editor," a position that did not require regular office attendance. In the mid-'80s he also began a second career, in advertising, starting as a copywriter for Barneys New York. After a few years and many awards, he became creative director of Barneys Advertising, honing his sartorial style and producing extraordinary ad campaigns. Since then he has also created advertising for such clients as Calvin Klein, Ian Schrager Hotels, Swatch, Dior, Nike, Armani, Fila, Rock the Vote, Song Airlines, and Air America, among many others.

Aside from having his Calvin Klein campaign investigated by the FBI, he is also notorious for his work on Madonna's Sex book. In addition to GQ, his work appears regularly in Vanity Fair, Italia, Paper, Purple, Self Service, L'Uomo Vogue, and Another Magazine. His books include The Style Guy, Soapbox (essays), and the poetry collection Human Nature (dub version). He is editor of the literary magazine Bald Ego and has a novel forthcoming.

He is married to Gina Nanni, a public relations executive, and has two sons. They live in downtown Manhattan and Litchfield County, Connecticut.