Mary Ng was first elected in a 2017 by-election. Prior to her election, she was the director of appointments in the office of Prime Minister Justin Trudeau. Her riding of Markham-Thornhill was previously held by Liberal John McCallum, who resigned his seat after being named Ambassador to China.
Her nomination as the Liberal candidate was the subject of some controversy after others also running claimed it was rigged in favour of Ng, due to her close association with Trudeau. The Liberal party says the process was run in accordance with national nomination rules.
She previously worked for the Ontario Public Service, Ryerson University, and as a staffer at Queen’s Park in the office of the Ontario Minister of Education.
Ng immigrated to Canada from Hong Kong with her family, and grew up in North Toronto.