Ross drove in two runs and scored on -- and his seventh-inning single drove in Buster Posey to cap a two-run rally that saw the Giants erase a 2-1 deficit and go on to defeat the Braves, taking the series 3-games-to-1 and advancing to the NL Championship Series for the first time since 2002.
Ross socked a solo homer in the sixth inning off Braves starter Derek Lowe (0-2) to forge a 1-1 tie.
Posey had two hits and an RBI to back Madison Bumgarner (1-0), who held NL wild-card winner Atlanta to two runs on six hits over six frames. Bumgarner walked one and struck out five.
Brian Wilson got the save despite allowing a pair of base runners in the ninth.
The Giants move on to face the Philadelphia Phillies in the NLCS, with the first two games to played at Citizens Bank Park starting Saturday.
Brian McCann homered for the Braves, who said goodbye to retiring Manager Bobby Cox.
Cox, 69, concluded a career that saw him guide the Braves to 14 division titles, one World Series win and 136 post-season victories.