In 1915, Cyril Coaffee began his competitive career with the North End Amateur Athletic Club. Five years later he won the hundred yard dash in 11.2 seconds at the 1920 Olympic trials in Montreal. Although the budget accommodated only a nine member team, Winnipeggers raised the necessary funds to send Coaffee to Antwerp, Belgium where he managed a third place finish in his heat but failed to qualify for the semi-finals.
At the 1922 Canadian Championships, Coaffee electrified the sporting world when he ran the hundred yard dash in 9.6 seconds, broke the Canadian record and tied Charlie Paddock's world record. Coaffee also won the 220 yard sprint and was considered one of the world's fastest human beings. In October of 1922, Coaffee teamed up with Laurie Armstrong, Billy Miller, and Peavey Heffelfinger to set a new Canadian record of one minute and thirty seconds in the 4 X 220 yard relay. In 1924 at the Olympic trials, Coaffee tied the Olympic record with a 10.8 second time in the 100 yard dash and went to the Paris Games as Canada's team captain. After the Olympics, Coaffee had an astonishing number of victories in a series of track meets in Britain and competed internationally with his most significant wins being over Canada's famous Percy Williams in 1926 and 1928. Coaffee's loss to Williams in the final of the 100 yard sprint at the 1928 Olympic trials signalled the end of Coaffee's running career.
Coaffee was known for his extreme forward lean, that was due to a partial paralysis in his right arm, and when he ran it appeared as if his legs were spitting out from beneath him. Coaffee held three Canadian records and was posthumously inducted into Canada's Sports Hall of Fame in 1956.