The Pope John Lions compete in the
Northwest Jersey Athletic Conference, which is comprised of public and private high schools in
Morris, Sussex and
Warren counties, and was established following a reorganization of sports leagues in Northern New Jersey by the
New Jersey State Interscholastic Athletic Association (NJSIAA). Until the NJSIAA's 2009 realignment, the school had participated in the
Sussex County Interscholastic League, which included public and private high schools located in Sussex County and northern Morris County. With 510 students in grades 10-12, the school was classified by the NJSIAA for the 2019–20 school year as Non-Public A for most athletic competition purposes, which included schools with an enrollment of 381 to 1,454 students in that grade range (equivalent to Group II for public schools). The football team competes in the United White 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 Non-Public Group B (equivalent to Group I/II for public schools) for football for 2024–2026, which included schools with 140 to 686 students. The 1964 baseball team won the Non-Public C state championship, defeating
Saint James High School in the tournament final. Since the playoff era started in 1974, the school's
football team won 18 state championships under coach Victor Paternostro. The football team won the NJSIAA Non-Public B North state sectional title in 1975, 1979, 1981–1983, 1986–1991 and 1993, and won the Non-Public II titles in 1995-1998, 2001 and 2002. The 1975 team finished with 10–0 record for the season and extended its streak to 34 games without a loss after a 14–6 win in the championship game against
St. Mary High School gave the team the Parochial B North title. The 1979 team had a 10-0-1 record after winning the Parochial B North final over
Immaculate Conception High School of
Montclair by a 28-0 score. A 28-0 win against
St. Cecilia High School in the 1981 Parochial B North championship game gave the team a 10-1 record for the season. A 27-0 championship game win against Immaculate Conception of Montclair gave the team the 1982 Parochial A North state sectional title. The 1983 team finished the season with a record of 11-0 after winning the Parochial B North sectional title with a 40-14 win against
Saint Joseph of the Palisades High School in the championship game. The 1986 team took the Parochial B North title and finished the season at 10-1 after a 35-0 win against
Phillipsburg Catholic High School in the championship game. The 1987 team's 22-7 championship game win against
Morris Catholic High School gave the team the Parochial B North sectional title and an 11-0 season record. A 35-0 win against
Marist High School in the championship game gave the team an 11-0 record and the 1991 Parochial B North title, and making Pope John the first program in the state to win six straight state football titles. The 1993 team won the inaugural Parochial Group II title with a 14-0 win in the championship game against Marist to finish the season with a 10-1 record. The 2001 team used a strong defense to finish the season with a 9-1 record after winning the Parochial Group II state title by defeating
Paterson Catholic High School by a score of 13-12 in the finals. In 2002, the football team won the Non-Public II state sectional championship with a 41-12 win against
Queen of Peace High School in the tournament final. In 2009, Coach Paternostro became New Jersey's winningest high school football coach with the Lions' win over
West Morris Mendham High School. Paternostro resigned from his coaching position after the 2010 season, leaving with an overall record of 373-68-5 in 43 seasons, including 20 state championships, 19 Sussex County Interscholastic League titles and two NJAC titles, and was replaced by Brian Carlson formerly from
Kean University. The wrestling team won the Non-Public Group B North state sectional championship in 1980–1983 (as co-champion in 1980), 1986, 1988, 1992, 1994 and 2018-2020. The team won the Non-Public Group B state title in 1982, 1983, 1986, 1992 and 2018. The boys tennis team won the Non-Public Group B&C state championship in 1982, against runner-up
Saint Mary's High School (South Amboy) in the final match of the tournament. The girls' outdoor track and field team won the Non-Public Group B state championship in 1984-1990 and won the Non-Public B title in 2006, 2007 and 2012-2014. The program's 12 state titles are tied for the most in the state and the streak of seven consecutive titles from 1984 to 1990 is tied for the second-longest statewide. The 1990 team won the program's seventh straight Parochial B title, defeating
Mater Dei High School by 45-32 in the finals. The boys track team won the spring / outdoor track title as Non-Public B champion in 1990, 1991, 1993 (as co-champion) and 1994. The 1990 team won the program's first championship, defeating
DePaul Catholic High School by 51-32 in the Parochial B finals. The girls swimming team won the Non-Public B state championship in 1995. The field hockey team won the North I Group II state sectional championship in 1996. The girls cross country running team won the Non-Public Group B state championship in 2001 and the Non-Public A title in 2005. The boys track team was the indoor track Group II state championship in 2004 and the Group I title in 2007. The girls indoor track team won in Group I in 2007, and in Non-Public A in 2013 and 2014. In 2005–06, the hockey team advanced to the state semi-finals, where they lost 3-2 to the
Delbarton School. The 2003-04 team was the champions of the Northern Red division, going undefeated in conference play and winning the conference tournament. The 2002-03 team had lost the previous year in the conference championship game after winning the conference regular season title. During the 2018-19 season the team captured the Gordon National Division Title and finished ranked number 4 in the state in NJ.com boys ice hockey rankings. In March 2008, the Pope John ski team won its first state championship. The boys basketball team won the Non-Public Group A state championship in 2015, defeating
Christian Brothers Academy in the final of the tournament. The program won the 2015 title with a 71-35 win in the playoff final against Christian Brothers Academy. ==Student organizations and clubs==