Hinson, 37, won Iowa's 1st Congressional District by about 11,000 votes over Finkenauer, 31.
"I am honored to be the Congresswoman elect for Iowa’s first district! Tonight we sent a message, the chaos and dysfunction we see in Washington is unacceptable to Iowans and voters expect more," Hinson said in a statement.
Finkenauer was vying for a second term after being elected in a blue wave in the 2018 midterms.
Hinson will now represent a district President Donald Trump won by four percentage points in 2016.
Hinson began serving in Iowa's House of Representatives in 2017 after working as a news reporter.
Hinson promised to tackle issues that matter to Iowans, including reforming the healthcare system, lowering the cost of prescription drugs, and securing the U.S. border.
Finkenauer has not issued a concession statement.
Her campaign didn't respond to a request for comment.
Businesswoman Nancy Mace won South Carolina’s 1st Congressional District, State Sen. Stephanie Bice won Oklahoma’s 5th Congressional District, former television journalist Maria Elvira Salazar prevailed in Florida’s 27th Congressional District, businesswoman Yvette Herrell won in New Mexico’s 2nd District, and former Minnesota Senate president Michelle Fischbach triumphed in the state’s 7th Congressional District.
As of 1 p.m. Eastern Time, Republicans had won 180 House seats, according to projections from Decision Desk.
Democrats had won 191.
Democrats were tracking four seats down from their total in the 116th Congress.
Democrats held 235 seats at the beginning of 2019, compared to the GOP's 199. By October of this year, that number had shifted to 232-197 because of issues including criminal charges.