O’Brian has taught at York University, Toronto, Harvard University, Cambridge, The University of British Columbia, Vancouver, and Ritsumeikan University, Kyoto. At the University of British Columbia, he was appointed assistant professor in 1987, associate professor in 1991, and full professor in 1998. He chaired the University Art Committee from 1993-2014 and the Program in Canadian Studies from 2002-05. He also held the Brenda & David McLean Chair in Canadian Studies from 2008-11 and was an associate of the Peter Wall Institute for Advanced Studies. He taught undergraduate and graduate courses, in addition to supervising MA and Ph.D. theses. He also organized numerous field trips for students. Following the election of Donald Trump as president of the United States in 2016, he canceled a field trip to New York because, he said, “worms are crawling out of the ground all over America [and I will] not crawl with them.” Students circulated a petition denouncing the cancellation. He has lectured across North America as well as in Europe, Australia, China, India, Israel, Japan, Mexico, Palestine, and South Africa. He was the Shastri Indo-Canadian Institute Visiting Lecturer in India in 1996-97 and visiting research professor at Ritsumeikan University in Japan in 2007. Museums and galleries O'Brian has been professionally involved with museums and galleries as a curator, exhibitor, researcher, advisor, and board member. From 1989-1991, he was a member of the board of the Vancouver Art Gallery, and from 1991-98 a special advisor to the board of the National Gallery of Canada, In 2020 was appointed an external advisor to the National Gallery. He has also been involved with the Harvard University Art Museum, Polygon Gallery, and the Morris and Helen Belkin Art Gallery. He maintains an occasional art practice. His work has been exhibited at public and private galleries: Octozilla (2018), produced with Gregory Coyes, was shown at the Vancouver Art Gallery; Ci elegans (2017), produced with Marina Roy, at SFU Galleries, Vancouver; Sixteen Nuclear Power Stations (2013) at the Art Gallery of Ontario, Toronto; Multiplication (1998) at the Catriona Jeffries Gallery, Vancouver; and More Los Angeles Apartments (1998) at Gagosian Gallery in New York and Los Angeles. “More Los Angeles Apartments unfolds as a peripatetic meditation on Edward Ruscha’s photobooks, personally placing O’Brian in geographical and conceptual proximity to Ruscha’s earlier work.” Publications O'Brian is the author or editor of twenty books and many articles. Some have been translated into French,