Returning from an ankle injury, Brown capped Auburn's game-winning drive with a 17-yard touchdown run with 2:19 remaining. The Nittany Lions reached the Tigers' 42 on their final possession before time expired.
"I really don't think it (the injury) was much of a factor," said Brown, who went over 1,000 yards for the season, of his ankle injury. "I had a pretty good week of practice and felt pretty strong coming into the game. In the beginning of the game, I felt comfortable."
Prior to this game, the Big Ten had been 4-0 in bowls as Wisconsin, Minnesota, Purdue and Michigan all won as underdogs.
Penn State (9-4) lost as a favorite. After a two-year absence, the Nittany Lions made their 31st bowl appearance in 37 years under coach Joe Paterno, but were held without a touchdown.
"There was a period there when a lot people doubted we would be a competitive football team at this level again," Paterno said. "I would hope they don't let this one distort some of the great things they did, and some of the things that happened to us."
The Nittany Lions failed to reach 10 wins for the 19th time in school history and dropped to 20-10-1 in the postseason under Paterno, the active leader in bowl wins and appearances.
Auburn avenged a 43-14 loss to Penn State in the 1996 Outback Bowl, the only previous meting between the teams.
"We're a physical football team," Auburn Coach Tommy Tuberville said. "We're a totally different team than we were last year. This team's got a lot of character."
The defenses dominated as Robbie Gould kicked a pair of field goals in the first half to give Penn State a 6-0 halftime lead.
Auburn (9-4) took its first lead, 7-6, on Brown's one-yard touchdown plunge with 4:52 left in the third quarter.
The Nittany Lions regained the lead on Gould's third field goal, a 32-yarder with 10:l0 left in the contest. Penn State failed to pick up a first down and, after having a second and two at the 11 and had to settle for the field goal.
But Damon Duval's 53-yard punt pinned Penn State back at its one-yard line and the Nittany Lions were forced to give up the ball after gaining just four yards.
Auburn started at the Penn State 40 with just over five minutes left and gave the ball to Brown five straight times after Jason Campbell completed a six-yard pass to Robert Johnson for six yards. Brown gained all but six yards on the six-play drive.
"We tried to shoot ourselves in the foot in the first half," Tuberville said. "We decided running the football was going to win the game for us and obviously Ronnie did a great job for us."
Penn State running back Larry Johnson, who became just the ninth player in NCAA history to rush for more than 2,000 yards, was limited to just 72 yards on 20 carries.
"When you look at my carries compared to his (Brown's) 37 carries, he better have 100 yards," Johnson said. "If you have 20 carries against a good defense, there is a good chance you won't even go over 100 yards. I don't think they shut me down as much as I shut myself down, slipping and falling."
Zack Mills also struggled for the Nittany Lions, completing just eight of 24 passes for 67 yards and an interception. Penn State was held to 268 total yards.
"We tried to get the ball to Larry more," Mills said. "Obviously, he's a Heisman Trophy candidate. We wanted to get it to him more, but that's how the game went."
"We knew we that we couldn't allow them a lot of points and wait for our offense to get the momentum going," Auburn linebacker Dontarrious Thomas said. "We just couldn't let them get into our end zone. As long as we kept them kicking field goals, our offense was going to be in the game."
Auburn relied almost totally on Brown, who rushed for all but 16 of the Tigers' 200 yards on the ground. Campbell completed 10 of 17 passes, but threw for just 78 yards.
"Personally, (facing Johnson) gave me a lot of motivation," Brown said. "If you're going to go up against someone like that, it gives you a lift going into the game."