Henry M. Gunn High School is one of two public high schools in Palo Alto, California. Gunn High School is a four-year high school with a current enrollment of just over 1,900 students.

Established in 1964, Gunn High School was named after the late Henry M. Gunn (1898–1988), who served as the Palo Alto superintendent from 1950 to 1961. In 1964, the Palo Alto Unified School District announced it would name the district's third high school after him. The Class of 1966 was the first class to graduate from Gunn High School.

The academic year has two semesters with 240 minutes of weekly instruction for every class. The school's schedule operates on a rotating bell schedule with classes assigned to lettered "periods" from A through G.

In the spring of 2010, Gunn High School was picketed by the Westboro Baptist Church. Rather than responding with violence, students and staff staged a successful counter-demonstration in the form of a Phelps-A-Thon. As a result, the school received favorable press and publicity and raised more than $1,100.00 for its gay-straight alliance.

Gunn is well known for its academically rigorous environment and enjoys a spirited academic and athletic rivalry with nearby Palo Alto High School.