Bill Kennedy emerged on the Canadian swimming scene in the late 1960s and first gained national attention by coming in second in the 100 metre backstroke, behind Jim Shaw, at the Canadian Championships in 1967. He made his international debut for the country at the 1970 Commonwealth Games, where he took home gold medals in the 100 m backstroke and the 4x100 metre medley relay, alongside Bob Kasting, Bill Mahony, and Byron MacDonald. His next stop was the 1971 Pan American Games, where he earned silver in the 4x100 m medley relay (with Mahony, MacDonald, and Timothy Bach) and bronze in the 100 m backstroke. He was then selected to represent Canada at the 1972 Summer Olympics, where he won bronze in the 4x100 m medley relay (alongside Kasting, Mahony, Erik Fish, and Bruce Robertson) and was eliminated in the opening round of the 200 metre backstroke event. His final major international tournament was the 1974 Commonwealth Games, where he captured gold in the 4x100 m medley relay with Kasting, MacDonald, and Mahony. A graduate of the University of Michigan and the University of Western Ontario, he retired after these Games and took up coaching.