The Brewers had been outscored 27-14 in losing their first five exhibition games.
Lohse, projected as the opening day starter, allowed two hits and struck out four.
Reds starter Johnny Cueto gave up a run and three hits in three innings.
"Spring is a little boring, but it's what you have to do to get ready for the season," Cueto, coming off his first 20-win season, said through a translator. "I felt good even though you don't have a lot of time out there."
Maldonado, getting plenty of playing time with catcher Jonathan Lucroy still out with a hamstring problem, is hitting .556 for the spring (5 for 9) with a double, a triple and a homer.
"Maldy's trying to get MVP of the Cactus League," Milwaukee manager Ron Roenicke said. "It's always nice to win a game, although we still got sloppy on a couple of plays. But it was better and we had some good offense."
Shane Peterson had a two-run homer and Jason Rogers got three hits for Milwaukee.
The Reds scored all their runs in the ninth off reliever Tyler Cravy.
Reds: Cueto gave up his first run in five innings this spring, allowing singles to Scooter Gennett and Jean Segura to start the first. But he retired nine of the final 11 hitters, getting Brewers cleanup man Aramis Ramirez to foul out to first twice.
"It's good face the veterans because they take a lot of pitches and let you throw and throw, which is good for me," Cueto said.
Brewers: Lohse had a little mechanical issue with his delivery but the results were good. He struck out Brayan Pena and Todd Frazier to end the first and Brennan Boesch to end his outing in the third with runners on first and third.
"I was coming out of my delivery a little bit, but I was able to figure it out by the third inning," said Lohse, who has allowed one earned run with seven strikeouts in 5 2-3 innings. "We're down here to learn how to consistently deliver the ball. It doesn't matter to me who I'm facing."
Brewers: Milwaukee expects 1B Adam Lind to make his first Cactus League appearance Thursday against Colorado. He has been slowed by lower back stiffness. He has battled back problems for the past four years. ... C Jonathan Lucroy will play in minor league games on Thursday and Friday with an eye toward a Cactus League game as the next step.
PUT IT ON THE VISA
Brewers closer Francisco Rodriguez has received approval for a visa in his native Venezuela and should join the team within a few days.
The 33-year-old Rodriguez is used to being a late arrival to camp. Last year, political strife kept him home until a few weeks into camp. And once he arrived, he stepped on a cactus spine in his bare feet to set him back further.
Reds: Cincinnati will face the Royals with LHP Paul Maholm taking his turn in the rotation.
Brewers: Milwaukee and RHP Matt Garza will face the San Francisco Giants in Scottsdale.