The school first opened in September 1963 to sophomores and juniors (incoming seniors continued to attend Monterey High School until graduation), graduating its first class in June 1965.

The school serves the communities of Seaside, Monterey, Marina, Sand City, and Del Rey Oaks.

Its student body reflects the region's diversity of language, ethnicity, nationality, and cultures.

Seaside High School has a very rich history in sports.

The football team is consistently top ranked around Monterey County and has won two CCS titles.