Williams was drafted in the fifth round of the 1952 NFL Draft by the Chicago Bears, where he played from 1952 to 1963 and was part of the Bears' 1963 NFL Championship team. He played defensive end and tackle with sporadic appearances at linebacker, a versatility that "Chicago Tribune" writer Cooper Rollow suggested led to his lack of accolades as he was never named All-Pro. Nicknamed "Fat Freddy", he was popular among fans and media for his humor, frequently joking about various team-related situations; in 1959, when asked if the Bears' defensive line was the best in the league, he remarked, "I don't know if we're the best, but we sure are the ugliest."