He is the son of Roy Thomson, the founder of Thomson Corp., a Canadian newspaper chain. Kenneth Thomson succeeded his father as chair of Thomson Corp. in 1976, and was, in turn, succeeded as Chair by his son David 2002.
Thomson is a well-known art collector. He holds the record buying for the most expensive picture ever sold in Canada: Paul Kane's Scene from the Northwest, for which he paid Can $5.06 million in 2002. That same year he announced a major financial donation (around C$50 million) to the Art Gallery of Ontario, with the plan that his collection would eventually end up there. His collection is worth an estimated C$300 million.
Thomson is married with three children, David, Peter and Lesley.