Templeton was born in Helena, Montana, and attended Palo Alto High School in Palo Alto, California. He attended Stanford University, where he played on the football and rugby union teams. He received both his undergraduate and law degrees from Stanford.
In 1920, Templeton was on the United States Olympic team in rugby and the long jump. He was handicapped in his best event, the high jump, because he normally used the Western roll jumping style, which was considered illegal at that time. In the long jump, he finished out of the medals in fourth place, but the U.S. rugby team upset France to win the gold medal.
In 1922, Templeton returned to Stanford as its track coach, a position he held until 1939. During his tenure as coach, Stanford won the NCAA Men's Outdoor Track and Field Championship in 1925, 1928, and 1934, and Stanford athletes won 19 individual titles. He was noted at the time for conducting intensive daily practices, an uncommon practice at that time. He later coached at the Olympic Club in San Francisco.
Templeton also had a career as a journalist and broadcaster. For his coaching, he was inducted into the USA Track & Field Hall of Fame in 1976, and is a member of the Stanford Athletic Hall of Fame in recognition of his coaching and as a football player.