A promising youngster with the Columbia Club, George Jessup later became a member of the boxing section of the Mildmay Rowing Club. Scheduled to compete in the ABA Championships in 1907, he did not compete but, having done well in local club competitions, rose to fame in 1908 when he reached the ABA lightweight final, where he lost to a man who would be a fellow Olympian a few months later, Harold Holmes. At the Olympics, Jessup suffered a second round knockout by Fred Spiller, who went on to win the silver medal. Jessup later boxed out of the Central Markets BC.