The first round was set when Jonathan Sanchez and the Giants eliminated the Padres 3-0 to win the NL West. That gave the Braves the wild-card spot, and they'll take on San Francisco starting Thursday.
Philadelphia and Cincinnati will meet in the other NL division series.
"We nailed it," Giants outfielder Pat Burrell said. "It was looking like it was heading the wrong way. Our guys toughed it out."
Tampa Bay clinched the AL East when the World Series champion New York Yankees lost at Boston 8-4. That sent the Rays back home to open the playoffs against Texas, while the wild-card Yankees will start their best-of-five series at Minnesota.
The action begins Wednesday afternoon at Tropicana Field, followed by games at Citizens Bank Park and Target Field. The banged-up Braves visit Tim Lincecum and the Giants at AT&T Park on Thursday night.
The Giants' win simplified the playoff scenario. Had they lost, San Francisco, San Diego and Atlanta would've all finished at 91-71, forcing a pair of tiebreakers. The Giants make their first postseason appearance since 2003, when the team was built around Barry Bonds.
The Yankees and Tampa Bay started the day even at 95-66, with both teams already guaranteed playoff spots. To win the AL East, the Yankees needed to finish ahead of the Rays, who held the tiebreaker after winning the season series 10-8.
In the ninth inning of the Rays' game at Kansas City, the Yankees' loss was posted on the scoreboard. Tampa Bay players briefly exchanged high-fives, then rushed onto the field after closing out a 3-2 win in 12 innings.
"It took a little of the tension off," Rays manager Joe Maddon said. "We wanted to win this game. How 'bout that? Extra innings, on the road, didn't need to win. It tells you something about our ballclub."