Born in Montreal, Quebec, Corcoran received a Bachelor of Journalism degree from Carleton University in 1969. After working for the Toronto Star in 1969, he joined the Ottawa Journal where he worked until 1971. From 1972 to 1974, he was a reporter and business editor for The Canadian Press. In 1974, he joined the Montreal Gazette where he worked as a business writer (1974—1976) and financial editor (1976—1978).

After traveling in Asia, he became associated editor of the Financial Times of Canada in 1978. He was appointed managing editor in 1980, executive editor in 1983, and was editor from 1984 to 1987. From 1987 to 1989, he was Associated Editor of the Financial Post. From 1989 to 1998, he was a business columnist for The Globe and Mail. From 1998 to 2000, he was hired by Conrad Black as an editor for the Financial Post.

In 1983, he was awarded the National Business Writing Award for Excellence in Editorial Writing and for Business Reporting and Writing in 1976. With Laura Reid, he co-authored the 1984 book Public money, private greed: the Greymac, Seaway, and Crown Trusts affair (Collins, ISBN 000217376X).

Corcoran is featured in the 2010 Canadian documentary film Water On The Table, where he debates water rights issues.

Charlie Smith, writing an opinion piece in the political blog for The Georgia Straight, states that Corcoran takes a libertarian viewpoint. He was characterised as a "conservative commentator" in Maclean's and a "right wing idealogue" by World Socialist Web Site.