Allen played for three seasons on the Penn Quakers football team until 1940, when he left to serve in the United States Army Air Forces during World War II.
[2] Upon leaving the military, he returned to Penn for his fourth and final season.
Allen was selected 94th overall (11th round, pick 4) in the 1946 NFL draft by the Chicago Bears.
The following year, Allen played for the Brooklyn Dodgers of the All-America Football Conference.
On January 10, 1958, Allen resigned as head coach in order to devote more time to an investment firm at which he had been recently given a major promotion.