Gov. Matt Blunt appointed Ron McCormick, 49, to the position Thursday to fill the vacancy created by the resignation of Jamie Burger.
Burger resigned from the position to become the county's presiding county commissioner on Jan. 1.
McCormick is a resident of rural Benton and recently became the owner of A&B Cleaners in Sikeston.
"I'm honored that the governor has chosen me and has confidence in me and I'll do my best," McCormick said. "I'm looking forward to working with Jamie and Dennis (Ziegenhorn, first district commissioner). I've worked with them in the past and I think we'll make a good team."