This article is about Australian rugby union referee. For author, journalist and college instructor, see Matthew O'Brien. For the New Zealand cricketer, see Matt O'Brien (cricketer).
O'Brien was born in Southland, New Zealand and is the son of former international rugby referee Paddy O'Brien. He studied pharmacy at the University of Otago where he played as a winger on the University's rugby team in the early 2000s, before he moved to the Gold Coast in Australia and established a pharmacy business.[1][2]