As one of the most influential and active governors in the National Hockey League at the time, Bill Jennings emerged as the architect of the league's dramatic expansion from six teams in 1967 to the 21 teams back in 1981. He served as chairman of the league's Board of Governors from 1968-1970, in addition to serving on or chairing virtually every other league committee in the last 20 years.

In 1966, Jennings originated the NHL's Lester Patrick Award Dinner, which annually honors persons for "outstanding service to hockey in the United States." He won the Lester Patrick Award himself in 1971. He was also instrumental in the establishment of the New York office of the NHL in 1964 and in the establishment of the Metropolitan Junior Hockey Association, as well as in the continued development of amateur hockey in the Metropolitan New York area.

Besides his distinguished hockey career, Jennings was active for over 25 years in the conduct of professional golf tournaments for the benefit of Westchester County hospitals. In 1967, he founded the Westchester Golf Classic and served as its general chairman, raising nearly $4,000,000 for the participating hospitals. He was also a member of the National Advisory Committee of the Professional Golfers Association of America.

In addition to his sporting interests, the Princeton graduate was a senior partner of the New York City law firm of Simpson Thacher & Bartlett, and a director of various major corporations. He was also honorary chairman of United Hospital in Port Chester, N.Y.

His contemporaries said it best of Bill Jennings: "He is one of professional hockey's most dynamic and successful executives for more than two decades, and has proven a most influential force in the dramatic and successful operation and expansion of professional hockey, in general, and the NHL in particular." The National Hockey League once recognized Jennings' contribution by naming him to the Hockey Hall of Fame in Toronto in 1976.