He worked at the Toronto firm of Harris & Partners until 1974, before enrolling at York University to study art and literature.

[6] O'Brian was also a member of the Pumping Station collective, a group of radical thinkers that met at the house of Gillian and Iain Boal, during the first half of the 1980s.

He has lectured across North America as well as in Europe, Australia, China, India, Israel, Japan, Mexico, Palestine, and South Africa.

[1] O'Brian has been professionally involved with museums and galleries as a curator, exhibitor, researcher, advisor, and board member.

O'Brian argues that the impact and global reach of Canada's nuclear programs have been felt ever since the bombing of Hiroshima and Nagasaki in 1945.

[11]  Douglas Coupland writes, "It finds beauty in grotesque places [and] validates the reader's Cold War paranoia.

"[12] Guest curated by O'Brian for the Art Gallery of Ontario in 2015, Camera Atomica was "the first substantial exhibition of nuclear photography to encompass the entire postwar period from the bombings of Hiroshima in 1945 to the triple meltdown at Fukushima Daiichi in 2011.

"[15] Matisse was an emblematic figure in twentieth-century art, perhaps the emblem of an artist whose work is predicated on the sensual pleasures of looking.

To promote his work, Matisse tried to show the media that whatever his reputation as an avant-gardist the conduct of his life was solidly bourgeois.

The book "casts a great deal of light on the way in which a picture becomes valuable… Patronage is as much a romance as a business transaction.

In an editorial written for The New Criterion, Hilton Kramer expressed admiration for Greenberg's criticism but distaste for O'Brian's politicization of it.

The University of British Columbia (Serge Guilbaut and John O'Brian) appears to be a happening place for art history.

"[19]Until the early 2000s, O'Brian's research focused on modern art history and criticism, primarily in North America.

Notable collections within the archives include correspondence with Clement Greenberg from 1981 to 1993 and atomic photographs (military, press, and vernacular), artworks, protest leaflets, propaganda pamphlets, corporate reports, government bulletins, newspaper front pages, and postcards.