TORONTO -- Aaron Hill picked a big moment to reach a major milestone.
Hill, who hit a solo home run, reached 100 RBI for the first time in his career.
"Nothing like a game-winning RBI to get your 100th," Blue Jays manager Cito Gaston said. "That's great for him. He's a kid that plays hard every day for you."
Hill was relieved to reach the century mark after going six games without an RBI.
"It was a nice hit," Hill said. "It's something you're not really trying to get to but it's in the back of your head. It's nice to get it over with and just play."
Shawn Camp (2-6) pitched one inning for the win.
Facing right-hander Dennis Sarfate (0-1), the seventh Baltimore pitcher, Jose Bautista walked to lead off the 11th. Hill followed with a double to right-center and Bautista scored without a throw.
Teammate Lyle Overbay collected the ball for Hill from a Baltimore player before joining the celebration at second base.
"Walkoffs are great, that's a great part of baseball," Hill said. "It's fun to see everybody run out of the dugout, coming to get you. That's what you work for."
Edwin Encarnacion hit two homers, a two-run drive and a solo shot, for the fourth multihomer game of his career as Toronto improved to 7-1 at home against the Orioles this season.
Baltimore's losing streak matches its season-high.
The Blue Jays trailed 5-4 heading into the ninth against Orioles closer Jim Johnson. Overbay came up as a pinch-hitter but struck out before pinch-hitter Adam Lind singled off Johnson's leg, Travis Snider hit a single to left and John McDonald loaded the bases with a single through the left side. Johnson's next pitch hit Bautista on the left elbow, bringing home the tying run and giving Johnson his sixth blown save.
"I still believe I can do the job but the last couple of outings haven't gone my way," said Johnson, who has blown saves in two of his past three outings. "I've got to try and right the ship here shortly."
Johnson sent it to extra innings by striking out Hill and Encarnacion.
Toronto loaded the bases in the 10th but Alberto Castillo got McDonald to pop out to first.
There were gasps when Hill, limited to 55 games last season because of a concussion, was hit on the left shoulder by a pitch from Danys Baez in the eighth. Two pitches later, Encarnacion homered to left.
"The home run ball kind of gave them a spark and got them back in it," Orioles manager Dave Trembley said.
Baez acknowledged being shaken up after losing his grip and nearly beaning Hill.
"That ball was really close to his face," Baez said. "It really had me scrambling a little bit when the ball left my hand."
Baltimore's bullpen has allowed 15 earned runs in 16 innings over the past four games.
"Baez had an opportunity to hold the lead and he didn't," Trembley said. "JJ had an opportunity to close it and he didn't. I'm sure they feel absolutely terrible and no one feels worse about it than I do."
Encarnacion and Hill homered to left on consecutive pitches in the third, the fifth time this season the Blue Jays hit back-to-back homers. Hill leads Toronto with 33 home runs.
Baltimore's Brian Roberts went 3 for 5 with a double. It was his 55th of the season, tying Lance Berkman's 2001 major league record for doubles by a switch hitter.
Attendance was 11,869, the fourth straight game the Blue Jays have drawn fewer than 12,000 fans. Toronto's all-time low is 10,074, set April 17, 1979, against the Chicago White Sox.
Toronto's Kevin Millar was thrown out at the plate when he tried to score from first on Randy Ruiz's double in the second, Baltimore's AL-leading 35th outfield assist.
Orioles outfielder Nick Markakis, who came in 6 for 43, was held out of the starting lineup for the second time this season. Markakis was not used as a substitute, making it the first game he's missed all year.
The Orioles have thrown out 16 runners at the plate, 13 at third base, five at second and have doubled one runner off first. ... Baltimore RHP Jeremy Guthrie (10-15) faces Toronto RHP Scott Richmond (6-10) in Wednesday's series finale.