Councillor Matt Perks has resigned from Port Pirie Regional Council.
Cr Perks, who gave notice effective from Thursday, will head overseas to pursue business interests.
He was the youngest member of the council and had worked as a hotel manager.
A council spokeswoman said the organisation thanked Cr Perks for his involvement in local government and his contribution since he was elected in November last year.
"We wish Matt and his partner Ebony all the best in their pursuit of building a business overseas which we are sure they will be successful with," the spokeswoman said.
"As required by the Local Government Act, Cr Perks' resignation will be tabled at the next ordinary meeting of council.
"In line with council's supplementary election policy and under the provisions of the Local Government (Elections) Act, council will not fill a casual vacancy until the next general election."
The next election is due in 2022.