With one out in the 11th, Royster singled to center field. Quinn Stewart followed with a double and Royster came home with the winning run when left fielder Concepcion Rodriguez couldn't play the ball cleanly.
Maiko Loyola went 4-for-4 with two doubles and a run scored, while Cesar Suarez went 3-for-5 with two RBIs to pace the Catfish (25-12), who have won five straight.
Ryan Reid (3-1) gave up one hit and struck out four in three innings of scoreless relief. Starter Ryan Morse allowed three runs on four hits over 6 1/3 innings with six strikeouts for Columbus.
The Catfish have now won 5 in a row, and 10 of 11. The home series with Rome continues Monday.