Born in Annapolis, Simmons attended public schools there and later attended the University of Maryland, where he was a starting defenseman for four years on the lacrosse team. Simmons helped Maryland to 23 straight wins and two undefeated national collegiate championships (1955 and 1956) during his four-year career, earning first team All-America honors in those two title seasons. In 1956, he was a member of the victorious South All-Star Team. Simmons also won the Powell Award for Service and Advancement of Lacrosse at Maryland and the William C. Schmeisser Memorial Trophy as the nation's outstanding defenseman in 1956.
After graduating with a degree in accounting, Simmons was drafted into the Army and served in Hawaii. After military service, he worked for an accounting firm in Washington, and from 1965-1970 he was the comptroller for Anne Arundel County government. From 1970 until his retirement in 2001, he owned private certified public accountant firms in Annapolis.
Simmons also continued to play and coach lacrosse after college. He played from 1959-1962 on the Annapolis Lacrosse Club, where he made the club all-star team in 1960 and 1961. He also coached youth lacrosse in Annapolis for several years. Simmons was inducted to the University of Maryland's Athletics Hall of Fame in 1989, and he was one of 19 Terrapins named to the ACC's 50th Anniversary Team in 2002. John Simmons passed away from Lou Gehrig's disease in 2003.