Incumbent Joni Ernst (R) defeated Theresa Greenfield (D), Rick Stewart (L), and Suzanne Herzog (I) in the election for U.S. Senate in Iowa. Ernst was first elected in 2014. 

The Democratic Senatorial Campaign Committee spent $28 million on the race. The National Republican Senatorial Committee spent $20 million.

Thirty-five of 100 Senate seats are up for election. Republicans have a 53-47 majority. Of the 35 seats up, 23 are held by Republicans and 12 by Democrats, giving Republicans greater partisan risk this year. Democrats need to win a net four seats to win an outright majority in the chamber.