The John F. Kennedy High School Knights compete in the Big North Conference, which is comprised of public and private high schools in Bergen and Passaic counties, and was established following a reorganization of sports leagues in Northern New Jersey by the New Jersey State Interscholastic Athletic Association. For the 2009–10 season, the school competed in the North Jersey Tri-County Conference, an interim conference established to facilitate realignment. Prior to that, the school had previously participated in Division C of the Northern New Jersey Interscholastic League (NNJIL), an athletic conference consisting of public and private high schools located in Bergen County and Passaic County. With 2,478 students in grades 10-12, the school was classified by the NJSIAA for the 2019–20 school year as Group IV for most athletic competition purposes, which included schools with an enrollment of 1,060 to 5,049 students in that grade range. The football team competes in the Liberty Blue division of the North Jersey Super Football Conference, which includes 112 schools competing in 20 divisions, making it the nation's biggest football-only high school sports league. The school was classified by the NJSIAA as Group V North for football for 2018–2020.