She won the Liberal Party's nomination for
Moncton—Riverview—Dieppe on March 28, 2015, and won the riding in the election held on October 19, 2015. On December 2, 2015, Prime Minister Justin Trudeau announced the appointment of Petitpas Taylor as deputy government
whip. On February 15, 2016, Petitpas Taylor was sworn in as a Member of the
Queen's Privy Council for Canada according to her duties as Deputy Government Whip. She then succeeded
Jane Philpott as
Minister of Health in a cabinet shuffle on August 28, 2017. She was re-elected in the 2019 federal election, and appointed Deputy Government Whip (for the second time) as well as a member of the
Board of Internal Economy. She was re-elected in the 2021 federal election. Petitpas Taylor stepped in as
Minister of Employment, Workforce Development and Official Languages following the resignation of
Randy Boissonnault on November 20, 2024. On December 16, 2024, strikers from the
Canadian Union of Postal Workers (CUPW) protested at Petitpas Taylor's
Moncton office in response to the Liberal government's motion to order them back to work. The RCMP was called to the scene but made no comment. Local union head Line Doucet indicated she spoke with and expressed her disappointment to Petitpas Taylor the previous day. Following the resignation of
Chrystia Freeland as deputy prime minister and finance minister, Prime Minister Justin Trudeau shuffled his cabinet on December 20, 2024. Petitpas Taylor was moved out of the three roles she held at the time - Minister of Veterans Affairs (which includes Associate Minister of National Defence); Minister of Official Languages; and Minister of Employment, Workforce Development and Labour - and was appointed
President of the Treasury Board. Petitpas Taylor continued in that role in
Mark Carney's
30th Canadian Ministry. After being reelected in the
2025 Canadian federal election in April, she was shuffled out of cabinet on May 13. ==Electoral record==