McGillicuddy played football for Harrison High School and then attended Princeton University on a football scholarship, playing defensive back on the college's undefeated football teams in 1950 and 1951. His roommate at Princeton was fellow football player Dick Kazmaier, who won the Heisman Trophy for 1951. John McGillicuddy later attended Harvard Law School and was hired by the law firm of Simpson Thacher & Bartlett after serving in the United States Navy.
He was hired by Manufacturers Trust Company in 1958. He was elected to serve as the bank's president in 1970 at age 39, making him one of the youngest people ever to run a major banking company, after his predecessor R. E. McNeil, Jr. announced that he would be stepping down.
During New York City's fiscal crisis during the 1970s, McGillicuddy helped organize the financial aid needed to bail out the city. He later played a key role in the late 1970s in the Bailout of Chrysler, working to organize the government loan guarantees that helped that company avoid bankruptcy. Following the merger, McGillicuddy became the chairman and chief executive of the combined institution, remaining with the bank until his retirement in 1993 when he was to be followed by Walter V. Shipley, who had been the chairman of Chemical.
The merger ushered in a wave of consolidation in the banking industry that continued with Chemical purchasing Chase Manhattan Corporation and assuming that company's name in 1996 and a December 2000 deal with J.P. Morgan & Co. that formed JPMorgan Chase & Co.
- Heinemann, H. Erich. "Personality:; 'New Kid' to Lead Manufacturers Hanover", The New York Times, July 5, 1970. Accessed January 8, 2009.
- Dash, Eric. "John F. McGillicuddy, 78, Banking Leader, Is Dead", The New York Times, January 6, 2009. Accessed January 8, 2009.
- Quint, Michael. "The Bank Merger; BIG BANK MERGER TO JOIN CHEMICAL, MANUFACTURERS ", The New York Times, July 16, 1991. Accessed January 8, 2009. "Chemical Bank and Manufacturers Hanover, two of New York's biggest banks, announced plans yesterday for the largest bank merger in American history."