Belinda Karahalios was elected a Member of Provincial Parliament in the Ontario legislature in 2018, representing the riding of Cambridge.  She is a co-founder of the New Blue Party of Ontario and lives in Cambridge with her husband, Jim Karahalios, and their son, Victor.  

In 2019, Belinda Karahalios introduced her first private member's bill - Bill 150, Ensuring Transparency and Integrity in Political Party Elections Act, 2019. Ford initially indicated his government would oppose the bill, then never allowed the bill to return from committee to third reading, and eventually killed the bill when they reset the legislative sitting in September of 2021. July 21, 2020, Belinda Karahalios was expelled from the Progressive Conservative caucus by Doug Ford after voting against Bill 195, the Reopening Ontario (A Flexible Response to COVID-19) Act, which would expand the government's emergency authority during the COVID-19 pandemic. Karahalios called the legislation an "unnecessary overreach on our parliamentary democracy." A month later, Belinda Karahalios, her husband Jim, and 17 other members of the Ontario PC Party were unlawfully removed from the Cambridge PC Riding Association Board as a result of the party executive, led by Brian Patterson, voting to "de-register" the riding association with Elections Ontario against the party’s own constitutional rules.

On October 12, 2020, Jim and Belinda Karahalios released a video announcing that they were forming a new political party, claiming that the Ontario PC Party was beyond redemption. Stating that there "is no party in the Ontario legislature defending the taxpayer, defending small business, defending places of worship, promoting freedom, promoting democracy or fighting political corruption." On January 7, 2021, the New Blue Party was officially registered by Elections Ontario. Party leader Jim Karahalios stated that the party would focus on supporting the taxpayer, places of worship and small business.