Unionville High School is a public high school of the York Region District School Board in Ontario, Canada. It is located west of the community of Unionville in the city of Markham. The school is located next to the Markham Civic Centre and the Markham Theatre.

The York Region District School Board (YRDSB), until 1999, English-language Public District School Board No. 16 is the English-language public school board for the Regional Municipality of York in Ontario, Canada. The York Region District School Board is the province's third-largest school board after Toronto's TDSB and Peel's PDSB, with an enrolment of over 122,000 students. It is in the fastest-growing census division in Ontario and the third-fastest growing in Canada.