Eglinski was first elected to represent the riding Yellowhead in a 2014 by-election.[3][4]
He was re-elected in the 2015 Canadian federal election with over 70 percent of the vote.[5] In the 42nd Canadian Parliament, his Conservative Party formed the Official Opposition. While he was not assigned to a critic role, Eglinski did introduce one private member bill into the House of Commons, An Act to amend the Criminal Code (abuse of vulnerable persons)(Bill C-206), which sought to make physical, emotional, sexual or financial abuse of a senior or someone who depends on others due to a mental or physical disability to be an aggravating circumstance for sentencing purposes. The bill was introduced on December 10, 2015, but did not advance to second reading.
In 2016, Eglinski surprised many by participating in the flag-raising to kick off Pride Week in Jasper, Alberta, a rare move for a Conservative MP. Acknowledging that he once opposed condoning homosexuality and saw no need for LGBT pride celebration, Eglinski credited his change of heart to the coming-out of one of his grandchildren.[6]
On 16 June 2017 Eglinski asked the government for a plan to protect the park from the pine beetle, and the residents who were "concerned for their own safety.. and the security of their homes," and the security of the tourists in the park. Catherine McKenna who was then Minister of the Environment and Climate Change offered to discuss this question in private.[8] Eglinski continued to raise the issue throughout his tenure in Parliament but he never managed to convince the government that there was a danger. Eglinski continued to pepper and prod the government, for example: "In June this year, the minister said in the House that she looked forward to discussing it further, but I have continued to repeatedly bring up the pine beetle issue because there has been no talk and no action."[9]
In late 2017, Eglinski faced nomination challenge for re-election from Ryan Ouderkirk, a parliamentary assistant to fellow MP David Yurdiga. "Surprised" by and "not happy" with the challenge, Eglinski announced in January 2018 that he would not seek re-election in 2019.[10]