Fischbach received 53.5% of the vote compared to Peterson’s nearly 40% with 1,328 out of 1,329 precincts reported.
“I am honored to have the outpouring of support from Minnesota families across #mn07,” Fischbach tweeted Tuesday. “I am grateful for the backing and am excited to hit the ground running in Washington to work on behalf of MN.”
President Trump endorsed Fischbach in March and asked Minnesotans to vote for her in the state’s primary election in August.
An October FiveThirtyEight report named Peterson the most vulnerable incumbent in the House of Representatives ahead of this year’s general election.
Peterson has been in office since 1991 representing Minnesota’s 7th Congressional District — the largest in the state — which leans more red than blue and voted for Donald Trump in 2016.