Rahway High School is a four-year public high school that serves students in ninth through twelfth grades from Rahway, in Union County, in the U.S. state of New Jersey, operating as the lone secondary school of the Rahway Public Schools. The high school's present location was built in 1941. The school has been accredited by the Middle States Association of Colleges and Schools Commission on Elementary and Secondary Schools since 1931; the school's current accreditation extends until July 2029.

As of the 2023–24 school year, the school had an enrollment of 1,270 students and 103.1 classroom teachers (on an FTE basis), for a student–teacher ratio of 12.3:1. There were 619 students (48.7% of enrollment) eligible for free lunch and 108 (8.5% of students) eligible for reduced-cost lunch.

The school was the 215th-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 191st in the state of 328 schools in 2012, after being ranked 261st in 2010 out of 322 schools listed. The magazine ranked the school 249th in 2008 out of 316 schools. Schooldigger.com ranked the school as 316th out of 376 public high schools statewide in its 2010 rankings (a decrease of 13 positions from the 2009 rank) which were based on the combined percentage of students classified as proficient or above proficient on the language arts literacy and mathematics components of the High School Proficiency Assessment (HSPA).

Rahway High School offers Advanced Placement courses in AP English Language and Composition, AP English Literature and Composition, AP United States History, AP United States Government and Politics, AP Comparative Government & Politics, AP Calculus, AP Statistics, AP Chemistry, AP Biology, and AP Physics.

Beginning in 2007 with support from Rahway alumnus and former Merck & Co. CEO P. Roy Vagelos, President of The Marianthi Foundation, the new Advanced Placement Incentive Program (APIP) was introduced. The APIP Program involves naming teachers as AP Teacher, Pre-AP Placement Teacher, Lead Teacher, and AP Advisor, providing financial incentives for students and teachers based upon AP enrollment and AP exam results.

Rahway High School seniors who are admitted to and attend a U.S. News & World Report ranked Top 25 National University or Liberal Arts College will receive a scholarship from the Marianthi Foundation. The Vagelos Scholarship, established in 2001, is funded by retired Merck and Co. CEO P. Roy Vagelos.

The Rahway High School Indians compete in the Union County Interscholastic Athletic Conference, which is comprised of public and private high schools in Union County and was established following a reorganization of sports leagues in Northern New Jersey by the New Jersey State Interscholastic Athletic Association (NJSIAA). Prior to the NJSIAA's 2009 realignment, the school had participated in the Mountain Valley Conference, which included public and private high schools in Essex, Somerset and Union counties. With 784 students in grades 10–12, the school was classified by the NJSIAA for the 2019–20 school year as Group III for most athletic competition purposes, which included schools with an enrollment of 761 to 1,058 students in that grade range. The football team competes in Division 3 of the Big Central Football Conference, which includes 60 public and private high schools in Hunterdon, Middlesex, Somerset, Union and Warren counties, which are broken down into 10 divisions by size and location. The school was classified by the NJSIAA as Group IV North for football for 2024–2026, which included schools with 893 to 1,315 students.

The boys' basketball team won the Class B (since reclassified as Group III) state championship in 1930, defeating Weehawken High School by a score of 24–16 in the tournament final played in front of a crowd of 5,000 at the 144th Regiment Armory in Elizabeth.