Smith earned 58.48 percent of the vote, with an overall 6,553 votes.
Mathis trailed behind by 1,900 votes — earning 41.52 percent of the vote for a total of 4,653.
Total number of votes cast was 11,206.
Smith will now advance to the November election, during which he will face Democratic candidate Carlotta Harrell.
Gary Barham earned majority vote against Bill Toney in the Henry County Board of Commission District 3 runoff race.
Barham received 2,305 votes for 59.55 percent and Toney earned 1,566 votes for 40.45 percent of the vote.
Barham will face Democratic candidate Sandra Vincent in November.
The elections results are currently unofficial, but are slated to be certified Friday.