Westfield High School is the public high school of Westfield. Located on the south side of town across from the Armory, the 1,800 student school contains over 80 clubs drawing 80 percent of the student body. Students regularly compete in academic contests across a range of disciplines and the student council and class officers meet with the administration to discuss student concerns. In the Class of 2008, 97 percent of the graduates pursued higher education, with 90.1 percent attending a four year college, 6.7 percent attending a two year college and .9 percent attending a technical school. 

The school offers over 170 courses in college prep, business, fine arts, music and practical arts during a five-period day. Over 65 percent of the student body studies at least one of the five foreign languages offered for three or more years. Fifty percent of the students take Advanced Placement classes and 68 percent take honors classes. In the Class of 2009, there are six National Merit Semi-Finalists.

The high school's newspaper, Hi's Eye, is a student-run weekly. It is the only high school newspaper in New Jersey that is not reviewed by the school administration before publication, and one of only a few in the country. The paper is self-funded through subscriptions and advertising. Published on 33 Fridays during the school year, there is a monthly entertainment insert, Iris. The Hi's Eye has won numerous national awards including from the Columbia Scholastic Press Association.

The existing building on Dorian Road was opened on February 4, 1952. There were expansions in 1960 and twice in the 1970s. In 2003, a new science wing was added to the building.

In 2008, Westfield High School was listed 27th amongst public school's on New Jersey Monthly magazine's annual list of top high schools in New Jersey. In 2006, Newsweek ranked WHS 691st amongst the top 1,200 high schools nationwide.

Notable alumni include cartoonist Charles Addams, physician Virginia Apgar, NFL quarterback Dave Brown, NFL punter Steve Cheek, Marvel Studios President Kevin Feige, Wired magazine founder Kevin Kelly, Tony Award nominated composer Matthew Sklar and NFL running back Harold "Butch" Woolfolk.

The principal of Westfield High School is Peter Renwick and the assistant principals are Mary Asfendis, James DeSarno, and Derrick Nelson.