Tustin High School is a public high school in Tustin, California, United States. It is part of the Tustin Unified School District. It was established in 1921 as the Tustin Union High School.

Tustin Unified School District was created from the 1972 voter-approved unification of the Tustin Elementary School District and the Tustin Union High School District. It is located in Tustin, a city in Orange County, California. Its district territory comprises Tustin, the unincorporated community of North Tustin, and parts of the cities of Irvine and Santa Ana. It has 18 elementary schools, five middle schools, four high schools, one K-8 school, and one adult school.