Born in Montreal, Quebec, Lacroix attended Collège Jean-de-Brébeuf before receiving a Bachelor of Law degree from the McGill University Faculty of Law in 1976.
He was admitted to the Quebec Bar in 1977 and received a master of Business Administration from McGill's Desautels Faculty of Management in 1981. He started practising law with the firm of O'Brien, Hall, Saunders in 1977. A senior adviser with the law firm Stikeman Elliott LLP, he was Executive Chairman of Telemedia Corporation from 2000 to 2003.
He also sat on the Boards of Donohue Inc., Circo Craft Co. Inc., Adventure Electronics Inc. and Michelin Canada Inc.
Lacroix is an associate professor with the Faculty of Law at Université de Montréal where he teaches in the securities, and mergers and acquisitions. He was a basketball colour commentator on Télévision de Radio-Canada during the 1984, 1988, and 1996 Summer Olympics.
He was also a weekly contributor for Radio-Canada's Hebdo-Sports radio show. His recent time in the Oasis Montreal Half-Marathon was 1:32:41.0. He was appointed president and CEO of the CBC, effective January 1, 2008, by Prime Minister Stephen Harper in November 2007 replacing Robert Rabinovitch.
Lacroix was re-appointed for a second term, on October 5, 2012.
He has been a member of the Board of Directors of Zarlink Semiconductors since 1992.