The Hackettstown High School Tigers compete in the Northwest Jersey Athletic Conference which is comprised of public and private high school in Morris, Sussex and Warren counties, having been established in the 2009-10 school year as a result of the realignment of conferences in Northern New Jersey by the New Jersey State Interscholastic Athletic Association (NJSIAA). With 656 students in grades 10-12, the school was classified by the NJSIAA for the 2019–20 school year as Group II for most athletic competition purposes, which included schools with an enrollment of 486 to 758 students in that grade range. The football team competes in the American 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 Group II North for football for 2018–2020. The school competes in interscholastic football, golf, soccer, cheerleading, volleyball, marching band, cross country, basketball, wrestling, fencing, baseball, softball, field hockey, lacrosse and track.