[10] Apart from classes in photography during high school, Hujar's photographic education and technical mastery was acquired in commercial photo studios, where he could use the darkroom during afterhours.

Early in 1967, he was one of a select group of young photographers in a master class taught by Richard Avedon and Marvin Israel, where he met Alexey Brodovitch and Diane Arbus.

In 1963, he secured his own Fulbright and returned to Italy with Paul Thek, whom he had been dating since 1959,[11] where they explored and photographed the Capuchin Catacombs of Palermo, images of the dead later featured in Portraits in Life and Death.

Hujar quit his job in commercial photography in 1967, and at great financial sacrifice, began to pursue primarily his own art work that reflected his homosexual milieu.

At the end of 1974, Hujar had an exhibition at the Foto Gallery on 492 Broome St, alongside pictures by Christopher Makos, where he didn't sell any of his work, but according to a friend gained a book contract with Da Capo Press.

Besides his friends like Susan Sontag, Fran Lebowitz, and Vince Aletti, he portrayed artists like John Waters, drag queen actor Divine and writer William S. Burroughs.

Both artists were gay white men who excelled at portrait photography and who made unashamedly homoerotic work that walked the line between pornography and fine art, but they were structural opposites.

Hujar had a wide array of subjects in his photography, including cityscapes and urban still lifes, animals, nudes, abandoned buildings, and European ruins.

"[12] Hujar's portraits, the subject of the first half of the one book he published while he was alive, are simple; he almost never used props and the focus of his work was on the sitter as opposed to the backdrop of the shot.

[3] A first retrospective of Hujar's work in collaboration with the estate was shown two years after his death at the Grey Art Gallery & Study Center of New York University.

In 2013 the Morgan Library & Museum in New York acquired a hundred prints and the entirety of his written estate and all contact sheets from the Peter Hujar Archive.

A collaboration between the Morgan Library and the Spanish Mapfre Foundation enabled a major travelling retrospective exhibition that was accompanied by a comprehensive monograph published in conjunction with Aperture in 2017.

[22] After his death several commercial galleries showed his work in (solo) exhibitions, like James Danziger (1991, 1992, 1998), Paula Cooper (1993, 2002), Wessel and O'Connor (1998), all situated in New York, Stephen Daiter in Chicago, Yezerski in Boston, and Berinson in Berlin (all three in 1999), Rodolphe Janssen in Brussels (1996), Renée Ziegler (1990) and Mai 36 (2002, 2010) in Zurich, and Maureen Paley and Marietta Neuss in London (both 2008).