Born in Windsor, Ontario, Canada in 1943, his father had been posted to Australia briefly by Ford and later encouraged his son to consider emigrating there.

He bought the right to open ten KFC franchises in Western Australia, raised $10,000 from each of thirty people to launch the business in December 1969, having moved with his wife and young child. Those who invested $10,000 then, had an investment worth around $8.9 million as of March 2006. After opening eight KFC outlets, he bought the rights to Burger King. Cowin later discovered someone else had the rights to the Burger King trademark in Australia, so Cowin instead called the outlets Hungry Jack’s. Many years later he had a falling out with Burger King over the name and other issues related to their franchise agreement which was eventually resolved in his favour. He talks about this in an interview for The Billion Dollar Secret book to which Cowin contributed.

Cowin was listed on the Australian BRW Rich 200 list at number 70 in 2008, and 79 in 2009, and had an estimated net worth of A$486m and an estimated value of A$538m in 2010. Cowin was ascribed a net worth of A$1.8bn (24th) in the 2016 BRW Rich 200. Despite this, in 2017, he has been noted for his miserliness with regards to weekend worker penalty rates within Australia, regarding them as a “thing of the past”. In 2019 the Financial Review Rich List, the successor of the BRW Rich 200, assessed Cowin’s net worth at A$2.79 bn; and was ranked as the 25th richest Australian. Meanwhile, Forbes Asia assessed Cowin’s net worth as US$1.7 bn in 2019; and he was ranked as the 23rd richest Australian by net worth.

In September 2015, Cowin was named the 22nd Chancellor of the University of Western Ontario. He made a donation to the University of Western Ontario to pay for the stands of the new football field, named after his father Stanley J. Cowin.