Ivy Lewis, who cannot drive a car, appeared at Merthyr crown court charged with obtaining£211.31 by deception and attempting to obtain a further£51.15. She had denied the charges.
A jury found the Independent councillor guilty of falsely claiming mileage for a 50-mile round trip from her home near Brecon to the council headquarters at Llandrindod Wells. She was caught by audit investigators, the court heard.
Mrs Lewis was released on bail and is expected to be sentenced in three weeks.