Sir William Mulock Secondary School is a secondary school located at 705 Columbus Way, off Mulock Drive in Newmarket, Ontario, Canada.

Prior to that, most of its students went to Newmarket High School.

The founding students have demonstrated the initiative of character traits by creating original 'character feathers' which can be found in the main hall.

The school is named after Sir William Mulock, an important figure in Canadian politics at the end of the 19th century, leading into the 20th century.

[2] He was one of the most prominent residents of Armitage, the first community established in King that has since been subsumed by Newmarket.