Hatcher hit the first pitch of the bottom of the ninth inning over the left-field wall to give the Jacksonville Suns a 1-0 win over the Tennessee Smokies and their second straight Southern League championship.
The Marlins' fifth-round pick in the 2006 Draft, Hatcher was 0-for-13 in the best-of-5 Finals when he came to bat against reliever Luke Sommer (0-1).
"You dream of hitting that ball and walking off," Hatcher said. "The guy threw me a fastball and I was going to hit it as hard as I could. And it just so happens I got it. If he threw me three changeups, though, I probably would have struck out."
The homer was Hatcher's second hit in 28 postseason at-bats.
"My timing has been screwed up, but I went up there in that last at-bat with a clear mindframe, 'Get your pitch and hit it,'" the 24-year-old catcher said. "I actually told Jason Delaney before the at-bat, 'I'm about to end this right here.'"
"It was just so fitting with Hatcher being the guy to do it. It was the perfect end to a perfect season," Suns manager Tim Leiper said. "He's been the backbone of our team. In the first half, he caught four out of every five games. He grinds it out. To grind it out like he did in this weather and take care of the pitching staff, it's fitting."
While the game was scoreless throughout, Leiper said there was never much doubt in the Jacksonville dugout.
"There was this thought that there was no way we were going to lose this game," he said. "Just knowing that if you get a run the game is yours, having homefield [advantage] really helped us, I thought. No matter how much we were down, the guys felt like they could win."
The Suns also defeated the Smokies in four games in last year's Championship Series and became the first Southern League team to win back-to-back titles since Montgomery in 2006-07.
"There are quite a bit of us that went through it last year," Hatcher said. "This series was going to come down to whoever made the first mistake. The two teams that deserved to be in it were in it. Give Tennessee credit."
Sandy Rosario (2-0) pitched the top of the ninth to get the win. He allowed a leadoff single to Brandon Guyer, then got Blake Lalli to hit into a double play and struck out Robinson Chirinos.
Jacksonville's Jose Rosario allowed three hits and fanned five over six innings after going 5-4 with a 3.24 ERA in 17 regular-season starts.
"He showed a lot," Leiper said. "He's got a lot of savvy. He's the kind of guy that got better and better, and it showed that he's a big-game pitcher. It says a lot about the guy's makeup when he goes out and pitches like he did."
Leiper wrapped up his first season as Suns manager after guiding Class A Advanced Jupiter to a 67-70 record in 2009.
"This was special. It's the first time as a manager I've won a league championship," he said. "I'm happy for the guys, the effort they put in, the way they are in the clubhouse. I couldn't be happier for them."
Smokies starter Craig Muschko was brilliant for seven innings. He allowed one baserunner -- Jeff Corsaletti singled in the third -- and struck out six.