The former Indiana star came through, launching a double off the center-field wall that brought home Arismendy Alcantara for a walk-off win.
Schwarber joined Iowa this week after a short stint with the big league club in which he hit .364/.391/.591 with a homer and six RBIs in six games.
"He really handled himself well in the clubhouse and with his teammates," Cubs general manager Theo Epstein told MLB.com's Carrie Muskat after Schwarber was optioned to Iowa. "I think he earned a lot of respect for his approach to this game, probably learned a few things about what goes into being a big leaguer.