The loss drops Atlanta to 0-4 for the first time since losing 10 in a row to open the 1988 season. The Astros are 3-1 after finishing last season with baseball’s worst record.
Houston trailed 3-0 in the third before a trio of errors by the Braves, including two from third baseman Juan Francisco, led to three unearned runs to tie the game.
Astros starter J.A. Happ drove in the go-ahead run with a single in the fourth inning. Pinch-hitter J.D. Martinez and Jose Altuve drove in a run each in the sixth to stretch the lead to 6-3.
Happ (1-0) allowed six hits and three runs with five strikeouts in six innings.
Braves starter Brandon Beachy (0-1) allowed four hits and four runs – one earned – in five innings.
Maxwell, acquired from the Yankees on Sunday, hit a towering two-run homer as a pinch hitter in the eighth inning.
Francisco, who the Braves acquired from Cincinnati on April 1, had three of Atlanta’s errors starting in place of Chipper Jones, who is on the disabled list.
The Astros got four hits and drove in two runs in the sixth inning off Livan Hernandez, who signed with the Braves after he was released by the Astros in spring training.
Houston relievers Wesley Wright, Fernando Rodriguez and David Carpenter combined to allow one hit in three scoreless innings.
Rookie Marwin Gonzalez had three hits and scored three runs for Houston.