McAfee was the second overall pick in the 1940 NFL draft. Nicknamed "One-Play McAfee", he was known for explosive speed; he ran a 100-yard dash in 9.7 seconds. In his first professional game, McAfee returned a punt for a 75 yard touchdown with 30 seconds to play to beat the Brooklyn Dodgers. Later in his rookie season, he ran back a kickoff for 93 yards and threw a touchdown pass to help the Bears win over their rival, the Green Bay Packers. In the final game of the season, the 1940 NFL championship game, McAfee returned an interception for a 34-yard touchdown during the 73–0 victory over the Washington Redskins.