Modbury High School opened in 1965 with a total of seven teachers and 97 students who were all in Year 8. The facilities of the school were shared with Modbury South Primary School. The first matriculation (Year 12) class was formed in 1970.
The students were taught in what is still the main building, a traditional 1960s E-shaped structure. It accommodated a maximum of 850 students but in 1972, a peak enrolment of 1383 saw the introduction of transportable classrooms.