He was drafted by the Philadelphia Eagles in the fourth round (55th overall pick) of the 1962 NFL draft.[5] Despite having a matching offer from the Dallas Texans of the American Football League, he signed with the Eagles in December 1961.[6] He was the lone rookie slated to play in an early exhibition game in 1962,[7] but he sustained a slipped disc in a warmup prior to the game.[8] He missed the entire 1962 season due to the injury, and he was injured again during a pre-season game in 1963, this time injuring both his back and his knee. He was released by the Eagles at the start of the 1963 season but then recalled to the team.[9] He appeared in 12 games with the Eagles during the 1963 season.[5] He returned to the Eagles in 1964, but was cut at the end of August.[10]
^Tober, Steve. "A leader and great teammate: Byrne was part of Montclair's rich history", The Montclair Times, July 15, 2021. Accessed December 20, 2021, via Newspapers.com. "It was the heyday of Montclair High School football.... Lineman Bill Byrne was a big part of both the undefeated 1956 squad (9-0) – which is considered by some to be one of the two or three best teams in school history – and the once-beaten '57 edition, which battled back from late-season adversity to finish strong."
^"Bill Byrne". Pro Football Archives. Retrieved December 19, 2021.