Justin O’Brien is represented in the National Gallery of Australia, all state galleries, many regional galleries as well as many other public collections throughout Australia and overseas including the Pinacotheca Vaticano, Modern Art Section, Rome.

In 1965 O’Brien was staying on the Greek Island Skyros where he would return in 1967 with Brian Dunlop and Donald Friend. He settled in Rome later that year where he lived until his death in 1996. Christine France has commented on the ‘delight’ in O'Brien’s timeless still life work. The current work relates in subject and composition to Australian Native Still Life in the collection of the Art Gallery of NSW. 

Justin Obrien was the recipient of numerous awards including the 1951 Blake Prize. He was honoured with a retrospective in 1987 at National Gallery of Victoria as well as an exhibition at the SH Ervin Gallery the same year.