Massabesic High School, Pronounced "mass-uh-BEE-sik" is a public high school located in Waterboro, Maine, United States.

The school is part of the RSU 57 school system, which serves six southwestern Maine towns with a combined population of approximately 22,000 residents: Alfred, Limerick, Lyman, Newfield, Shapleigh and Waterboro.

Massabesic High School was first opened in 1969 with an enrollment of over nine hundred students within grades nine through twelve.

On August 29, 2007, Massabesic High School occupied the former Massabesic Junior High School building and declared it the East Building, expanding the high school and eliminating overcrowding problems.

The East Building contains the foreign language department and the NJROTC program.