Rep. Milo Smith, R-Columbus, has defeated GOP challenger and Bartholomew County council member Ryan Lauer, who ran his campaign largely on education issues.
Smith, who was first elected in 2006, has received 60 percent of the vote.
"I feel relieved," Smith said. "This is the first time I've had someone from my own party challenge me. I thought I was doing a good job and apparently there were people who thought I could do a better job, so that's my commitment. I'm going to try and do a better job representing people in my district."
Smith was criticized by some earlier this year for his role in passing HJR-3, the constitutional amendment to define marriage as between a man and a woman.
But Lauer did not make HJR-3 an issue in the race.
No Democrats ran in the primary election, but the Democratic Party could still choose a candidate via a caucus before the general election.