Smith is traveling the state this week to launch his campaign. He's an attorney and certified public funds investment manager.
Smith was a budget adviser for Gov. Haley Barbour, leaving the job in December. He now works for a private law firm.
The current state treasurer, Republican Tate Reeves, is running for lieutenant governor this year. Reeves has been treasurer for two terms.
Republicans Lynn Fitch and Lee Yancey also are running for treasurer. No Democrat has entered the race.
Candidates' qualifying deadline is March 1. Primaries are Aug. 2, and the general election is Nov. 8.