York Mills Collegiate Institute is a public high school in Toronto, Ontario, Canada. It is part of the Toronto District School Board, offering grades 9–12. It is located in North York along York Mills Road between Leslie Street and Bayview Avenue. Prior to 1998, it was part of the North York Board of Education.

The school emphasizes university preparation and academics. English and French Immersion courses are provided from grades 9 to 12. Windfields Middle School (half French immersion and half English) and St. Andrews Middle School are the two feeder middle schools that make up the majority of York Mills' population. Additionally, Don Valley Middle School is a feeder school to York Mills with only its smaller population of French immersion students.