He served as the general manager for the New York Giants of the National Football League (NFL) from 1947 to 1973 and remained with the team through 1993.

[3] He went undefeated in doubles play as a junior and senior and was known as a "fierce competitor"; according to the Fordham website, "Walsh liked to run around using his backhand and possessed a swooping forehand described by contemporaries as 'murderous'".

[3] After having worked for a time in the insurance field, in 1947 Walsh joined the New York Giants which was owned by Wellington Mara, a friend of his at Fordham.

[7] Walsh was removed as general manager and replaced by Andy Robustelli in 1974, but remained with the team as vice president and secretary.

[2] He stayed with the Giants through 1993 before announcing his retirement; he helped them win the Super Bowls for the 1986 and 1990 seasons.