Balcatta-based PS Structures has won a $15.6 million contract for an expansion project at Carine Senior High School.
The project will include the construction of general and specialist classrooms to accommodate an additional 300 students.
PS will refurbish three existing buildings, extend one structure and construct four new buildings.
Work is expected to begin later this month, with completion targeted for June 2019.
PS recently completed the main works for Yanchep Secondary School, which opened for the 2018 school year, and also completed construction work at Churchlands Senior High School.