Joy Smith, who represents the riding of Kildonan-St Paul, said Tuesday she is retiring after holding the seat since 2004.
"It's time for me to move on," she said at her Winnipeg constituency office.
Smith has been an outspoken activist against human trafficking during her time in Parliament and she said that work will continue.
"After taking time to consider my next step in the fight against modern-day slavery, I have decided that I can do more outside of Parliament," she said in a statement. "Following the next election, I will continue to support the survivors of human trafficking by devoting my time to the Joy Smith Foundation."
In 2007, her private member's bill condemning sexual trafficking of women and children across international borders passed unanimously.
Smith is the latest Conservative MP from Manitoba to choose not to run again in the election set for October.
Rod Bruinooge, who represents Winnipeg South, announced last week he is leaving federal politics to spend more time with his young children. He left the door open to running provincially.
The federal Liberals have candidates nominated in both city ridings. Winnipeg city councillor Jeff Browaty, who used to work for Smith before his election in 2006, told some news outlets he is considering running for the Conservative nomination.
More than 20 sitting Conservative MPs have announced they won't be running in the federal election. A handful of Liberals and NDP incumbents have also announced their retirements.
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