"It has been both a privilege and an honour to serve the people of Brampton and Queen’s Park," Jeffrey told reporters on Tuesday afternoon after news leaked that she would be leaving the legislature.
Jeffrey has served as a Liberal MPP since 2003. She has held several cabinet positions under Premier Kathleen Wynne and former premier Dalton McGuinty.
"I'm grateful to premiers McGuinty and Wynne for their confidence in me," she said.
Her cabinet resignation takes effect immediately. Jeffrey said she will formally resign from the legislature later Tuesday afternoon.
Her departure means that the governing Liberals will have just 48 seats in the 107-seat legislature. The Progressive Conservatives hold 37 seats, while the New Democrats hold 21.
Premier Kathleen Wynne released a statement on Tuesday, thanking Jeffrey for her service.
"I want to thank my friend Linda Jeffrey, for her dedication and leadership these past 11 years, on behalf of the people of Brampton-Centre and Brampton-Springdale, and all of Ontario," Wynne said in the statement.
Wynne is due to announce a cabinet shuffle at 3 p.m. A news release says the premier will be attend "the swearing-in of new members of her Cabinet," at that time.
Jeffrey had been serving as the province’s minister of municipal affairs and housing.