The game was a makeup for a May 15 rainout, and it marked the home finale. Cincinnati finished 43-38 at home this season, compared to 30-45 on the road.
Harang (6-16) seemed headed for a short outing once he fell behind by a 4-0 score after three innings. The game's second batter, Jeremy Hermida, hit a solo homer to right field in the top of the first.
The first four batters reached in the Marlins' second, with Cameron Maybin and Matt Treanor driving in a run each with RBI singles. More damage was prevented when third baseman Edwin Encarnacion stopped a hot line drive by Hanley Ramirez with runners on second and third.
There were two outs in the top of the third when Harang's 1-2 pitch was deposited into the left-field seats for a solo homer by Josh Willingham. After Willingham's homer, Harang buckled down and retired 16 of his last 19 batters and gave up just three more singles.
"I didn't have my best stuff today," said Harang, who gave up eight hits and two walks with six strikeouts over seven innings. "I was out there grinding. I think they realized that I was out there battling for them and trying to keep them in this game. They stepped up, big time, there in the seventh with that six-spot on the board for me. I appreciate it."
The Reds bullpen was stirring early, but manager Dusty Baker wanted to give Harang every chance to get a win. The right-hander wound up throwing 122 pitches.
"We wanted to get it for Aaron," Baker said. "He started out a little rough. We had guys up in the bullpen early in the ballgame because we certainly didn't want those guys to get too big of a lead. But Aaron settled down and made some quality pitches and we came back right on time."
Marlins starter Ricky Nolasco seemed to be cruising until the sixth. Nolasco retired 12 in a row until Votto hit his 22nd homer of the season with a 432-foot long ball to right field.
In the seventh with runners on second and third and no outs, pinch-hitter Ryan Hanigan hit a comebacker to reliever Andrew Miller (6-10) at the mound. Instead of going to first base, Miller hesitated before throwing home, and Danny Richar slid ahead of the tag. Corey Patterson appeared headed for a rundown on the play until Matt Treanor's errant throw sent him to third base.
Pinch-hitter Jolbert Cabrera's walk loaded the bases for Jerry Hairston Jr., who tied the game with a two-run single. With one out, Votto stroked an RBI double to left field. Pinch-hitter Andy Phillips added a two-run bloop single to shallow right field.
The crowd for the makeup game was announced as 13,565, but only around 4,000 fans were believed to be in attendance. Those who came saw something rare. It was only the fourth time in 28 starts that the Reds scored more than five runs during a game that Harang started.
"Harang extended himself and ended up getting a victory out of it," Baker said. "It's been a long time since we've scored him that many runs. It came right on time."
Whether it's been self-inflicted mistakes or bad luck, it's been the most trying of seasons for Harang. He easily established a career-high in losses and Monday's pair of solo homers gave him 33 allowed for the season -- second most in the National League.
A four-inning emergency relief appearance during an 18-inning loss at San Diego sent Harang's season off the deep end, and later, a right forearm injury cost him a month on the disabled list. The situation has been more optimistic lately. Harang has a 2.39 ERA over his last seven starts and was coming off a complete-game, six-hit shutout of the Cardinals on Wednesday.
"We wanted to give him a chance to win the game and end up this year on a positive note," Baker said.