Sir John A. Macdonald Collegiate Institute was designed by the architectural firm, Gordon S. Adamson and Associates. The school building, originally named O'Sullivan Secondary School, was constructed in 1963 and opened in the fall of 1964 when there was only farmland around it, and as the population in the area grew, so did the school. During construction, O'Sullivan was renamed to Sir John A. Macdonald Collegiate Institute, after Canada's first prime minister, John A. Macdonald, in which the colours red, black, white and purple were chosen, with the latter colour taken from the $10 Canadian banknote.
As its eleventh collegiate, the school's main building was then extended to have more classrooms, along with larger rooms used for music, art, and autoshop. MacDonald celebrated its 50th year on September 26, 2014.
