Though his early works focused on business and political history, he also wrote biographies of physicians Frederick Banting, William Osler and Harvey Cushing.

His doctoral dissertation, which was supervised by Ramsay Cook, was a social history of Canadian business, an analysis of the "thoughts and dreams" of businessmen in Canada during the National Policy years.

In 1978 he published a major biography of Sir Joseph Flavelle, "A Canadian Millionaire", and in 1987 the first history of business in Canada, "Northern Enterprise".

Like J. L. Granatstein, his criticism of excessively specialized social history has made him a controversial figure in Canadian historiography.

Bliss has been a frequent commentator on Canadian politics for newspapers, magazines, and television, and has lectured widely in North America and Europe.

[1] In 2011, he received the Lifetime Achievement Award from the American Osler Society in 2010[7] Bliss frequently commented on current events, contributing essays to various magazine and newspapers, including The Globe and Mail.