Born in Savannah, Georgia, Harmon spent much of his boyhood in Florida, in the Orlando area. A youthful prodigy, he qualified for the U.S. Amateur at age 15 in 1931. Harmon was a club professional when he won the 1948 Masters Tournament by five shots to earn $2,500. He was a semi-finalist three times in the PGA Championship (1945, 1948, and 1953), competing as a club pro against full-time tour players. Claude Harmon also finished in third place at the 1959 U.S. Open, which was held at his home course at Winged Foot.