Fair Lawn High School is a four-year comprehensive public high school serving students in ninth through twelfth grades, located in Fair Lawn, Bergen County, in the U.S. state of New Jersey, operating as the lone secondary school of the Fair Lawn Public Schools.

As of the 2024–25 school year, the school had an enrollment of 1,687 students and 124.7 classroom teachers (on an FTE basis), for a student–teacher ratio of 13.5:1. There were 168 students (10.0% of enrollment) eligible for free lunch and 190 (11.3% of students) eligible for reduced-cost lunch.

Approved in June 1941, construction of the building was delayed due to World War II and the challenges it caused in obtaining the materials needed to complete the project. The school, constructed at a cost of $700,000 (equivalent to $13 million in 2025), opened in September 1943 with nearly 900 students in seventh through eleventh grades in a building with 29 classrooms and a capacity to serve a maximum enrollment of 1,070 students. Those students from Fair Lawn in twelfth grade who had previously attended Hawthorne High School, Paterson Central High School or Ridgewood High School completed their studies at their receiving school through graduation.

For the 1990–91 and 1997–98 school years, Fair Lawn High School received the National Blue Ribbon Award of Excellence from the United States Department of Education, the highest honor that an American school can achieve.

In 1998, the school's principal was named the State Principal of the Year by the New Jersey Principals and Supervisors Association in recognition of her work, which included being the principal of the only public high school in New Jersey (as of that time) to have won two Blue Ribbon Awards for Excellence.

In its 2013 report on "America's Best High Schools," The Daily Beast ranked the school 876th in the nation among participating public high schools and 66th among schools in New Jersey. In 2012, Newsweek ranked FLHS in the top 4% of high schools in the nation based on how hard schools challenge their students with Advanced Placement and college level courses. In the 2011 "Ranking America's High Schools" issue by The Washington Post, the school was ranked 58th in New Jersey and 1,691st nationwide. In Newsweek's May 22, 2007, issue, ranking the country's top high schools, Fair Lawn High School was listed in 808th place, the 19th-highest ranked school in New Jersey.

The school was the 70th-ranked public high school in New Jersey out of 339 schools statewide in New Jersey Monthly magazine's September 2014 cover story on the state's "Top Public High Schools," using a new ranking methodology. The school had been ranked 65th in the state of 328 schools in 2012, after being ranked 76th in 2010 out of 322 schools listed. The magazine ranked the school 81st in 2008 out of 316 schools. The school was ranked 62nd in the magazine's September 2006 issue, which included 316 schools across the state. Schooldigger.com ranked the school tied for 72nd out of 381 public high schools statewide in its 2011 rankings (a decrease of 7 positions from the 2010 ranking) which were based on the combined percentage of students classified as proficient or above proficient on the mathematics (89.3%) and language arts literacy (96.8%) components of the High School Proficiency Assessment (HSPA).

Fair Lawn High School has an active extracurricular program encompassing diverse interests. The school has an award-winning musical theater program, as well as shows performed by the Masques (drama group), the Boptones (school rock band), and the orchestra.