Trailing 7-6 going into the inning, the Red Sox put runners at first and second on one-out walks to Jacoby Ellsbury and Dustin Pedroia. Gonzalez, the AL leader with 37 RBIs, then got the winning hit on the first pitch he saw from Kevin Gregg (0-1).
Alfredo Aceves (1-0) got the win, allowing one run in three innings.
The Orioles had led 6-0 before the Red Sox scored five runs in the sixth. Mark Reynolds' solo homer gave Baltimore a two-run lead in the seventh. Then Jason Varitek singled in a run in the bottom of the inning, making it 7-6.
Boston (21-20) went over .500 for the first time this season with its fourth straight win following a three-game road sweep of the New York Yankees.
Chris Tillman pitched five scoreless innings for the Orioles while they capitalized on Daisuke Matsuzaka's wildness to build their 6-0 lead.
On the opening pitch of the game, Brian Roberts reached first on a liner that struck Matsuzaka just above the belt. The next batter, Nick Markakis, drew the first of seven walks off the right-hander. One run then scored on a double by Derrek Lee and another on a groundout by Vladimir Guerrero.
Matt Wieters made it 3-0 in the third with an RBI single.
In the fifth, Matsuzaka left after walking two of the first three batters. Scott Atchison came in and gave up an RBI single by Reynolds and a sacrifice fly by J.J. Hardy.
Baltimore went ahead 6-0 in the sixth on a run-scoring single by Adam Jones.
But when Tillman left, the Red Sox came back.
J.D. Drew led off the sixth against Mike Gonzalez with a single and took second when the ball got by left fielder Luke Scott for an error. Jed Lowrie then doubled in Drew. Lowrie took third when Carl Crawford reached on a fielding error by third baseman Reynolds and scored on a single by Varitek.
Gonzalez retired Ellsbury on a fly to left. Jeremy Accardo came in and got Pedroia on a fly out to center before Adrian Gonzalez singled in one run and Kevin Youkilis doubled in two, making it 6-5.
Notes
Scott, who entered the game with 12 walks, walked four times. … Lee was listed as day-to-day after leaving the game in the bottom of the third with a strained left oblique. He was replaced by Jake Fox. … left The Red Sox placed RHP John Lackey on the 15-day disabled list with a strained right elbow and recalled Atchison from Triple-A Pawtucket. … The Orioles scored just nine runs while Tillman was in the game in his other seven outings. … Baltimore was successful on all four steal attempts.