With Penny back in the rotation, left-hander Brad Hand will go back to the bullpen.
Penny, 36, has made two starts this season, going 1-0 with a 4.50 ERA. He's also pitched twice in relief, including throwing one scoreless inning in Friday's 5-2 loss in Atlanta.
"He's done a nice job," Redmond said. "He's been in big games, big situations. He's earned it."
Before joining the Marlins in early August, Penny had not pitched in the big leagues since 2012. The veteran right-hander, who has All-Star and playoff experience, has been a bit rusty with his command. In 10 innings as a starter, he's walked seven and struck out six.
Hand has bounced back and forth from the bullpen to the rotation, going 2-6 with a 4.71 ERA. In his last start -- a loss at Colorado -- he gave up four earned runs on seven hits with three walks and three strikeouts in 4 1/3 innings.
As a starter, Hand is 2-6 with a 4.82 ERA, compared to a 4.34 ERA and no decisions in 15 appearances as a reliever.
Although Penny is getting the start on Tuesday, the team is handling the fifth spot on a per-game basis.
"We'll see," Redmond said. "I think I've been pretty consistent that we will take it one start at a time and see how Brad [Penny] does. We've kind of kept it open going from start to start at this point."
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter