Member of Parliament

The next federal election was held in May 2011, when Zimmer faced former provincial politician Lois Boone for the New Democratic Party, Prince George lawyer Ben Levine for the Liberal Party of Canada, and physiotherapist Hilary Crowley for the Green Party of Canada. During the campaign Zimmer said he would advocate for reduced spending until the federal budget was balanced but also lobby to direct federal funds to widen Highways 2 and the Alaska Highway to four lanes between the Alberta border and Fort St. John.^[6][7] He noted that he believed pensions for former politicians were too high and that he would seek pension reform.^[8] Zimmer won the election with 62.12 per cent of the vote.

During the 2015 federal election, Zimmer opposed another study into murdered and missing Aboriginal women during a heated local candidates debate, saying 42 previous studies had already been done and that a primary problem, as stated in the Royal Canadian Mounted Police report, was economic status or lack of a job.^[9] After the debate, the Union of British Columbia Indian Chiefs called for Zimmer to step down as a candidate. Zimmer had stated that, "One of the major drivers of missing and murdered aboriginal women is the lack of economic activity, or simply put, the lack of a job. … Ultimately, when people have a job, they're not in despair. They can stay on reserve, and that's where we want them to be, we want them to be happy where they live." Grand Chief Stewart Philip, the president of the Union of BC Indian Chiefs, characterized Zimmer's remarks as "simplistic" and "unacceptable".^[10] Zimmer later clarified his comments, stating that he was referencing the RCMP's report on Missing and Murdered Aboriginal Women which lists employment status as one of the risk factors of murdered Aboriginal women.^[11] Zimmer went on to say that, "I absolutely care about missing and murdered Aboriginal women and want to see it stopped. I have a wife and a daughter and a mother and it is a tragedy that we need to fix."^[12]

Zimmer was re-elected with over 50% of the vote,^[13] and his Conservative Party formed the Official Opposition for the 42nd Canadian Parliament. After outgoing Prime Minister Stephen Harper resigned as leader of the Conservative Party, Rona Ambrose took over as acting leader; she appointed Zimmer to be the deputy critic of Families, Children and Social Development (to Karen Vecchio). In May 2016, Zimmer sponsored and brought forward in the House of Commons a petition with 25,000 signatures advocating for the de-restriction of the AR-15 semi-automatic modern sporting rifle. A month later, when that weapon was used in the Orlando nightclub shooting, the petition and Zimmer's advocacy were criticized.^[14]

In the May 2017 Conservative Party leadership election, Zimmer endorsed Andrew Scheer.^[15] Following Scheer's victory, he reassigned Zimmer to be deputy critic of the Treasury Board. On April 6, 2017, Zimmer introduced his first private member's bill, Bill C-346 An Act to amend the Firearms Act (licences) which would eliminate the expiry of firearms licences, with a mandatory provision that the licence holder update his or her relevant information every 10 years. The bill was debated but defeated at the second reading stage in November 2017, with only the Conservative Party voting in favour.

In October 2019 he was re-elected again, this time with just shy of 70% of the vote. On November 29, 2019, Andrew Scheer named him to the Shadow Cabinet as Shadow Minister for Northern Affairs and Northern Economic Development Agency.