Motley grew up in Canton, Ohio. He played football through high school and college in the 1930s before enlisting in the military during World War II. While training in the U.S. Navy in 1944, he played for a service team coached by Paul Brown. Following the war, he went back to work in Canton before Brown invited him to try out for the Cleveland Browns, a team he was coaching in the newly formed AAFC. Motley made the team in 1946 and became a cornerstone of Cleveland's success in the late 1940s. The team won four AAFC championships before the league dissolved and the Browns were absorbed by the more established NFL. Motley was the AAFC's leading rusher in 1948 and the NFL leader in 1950, when the Browns won another championship.