Markham—Unionville is located in the City of Markham within an area bordered by a line commencing at the Highway 404-407 interchange, then east along Highway 407 to McCowan Road, north on McCowan Road to 16th Avenue, east on 16th to Highway 48, then to the northern city limit, then along the northern and western city boundaries to the 404-407 interchange.

[3] Ethnic groups: 66.6% Chinese, 12.1% White, 9.9% South Asian, 2% Black, 1.4% Filipino, 1.2% West Asian Languages: 29.5% Yue, 28.4% English, 20.7% Mandarin, 1.6% Tamil Religions: 51.2% No religion, 33.3% Christian (14.8% Catholic, 2.5% Christian Orthodox, 1.5% Baptist), 4.8% Buddhist, 4.8% Hindu, 4.8% Muslim Median income (2020): $34,000 Average income (2020): $52,900 It is located in the province of Ontario and covers suburban areas north of Toronto.

Markham—Unionville was the only seat that the Liberals lost among those they held after the 2011 election, though the riding's boundaries changed considerably and would have been won by the Conservatives in 2011 based on the redistributed results.

54% of Markham—Unionville's territory (mostly south of Highway 407) was redistributed into the new Markham—Thornhill riding for the 2015 election.

The area north of Highway 407 and west of McCowan Road remained in Markham—Unionville.