The Blue Jays led 2-1 heading into the eighth but Teagarden tied it with a homer off reliever Darren Oliver, his second.
Gonzalez left after Munenori Kawasaki hit a one-out single in the bottom half. O'Day came on and got Rajai Davis to ground into a fielder's choice, but Bautista followed with a two-out homer just inside the left-field foul pole on a 3-2 pitch.
"I made a terrible pitch," O'Day said. "If I make a good pitch, he's probably out."
The homer was the first allowed by O'Day since May 22, when Yankees rookie David Adams took him deep.
Oliver (3-1) worked one inning and Casey Janssen finished for his 17th save in 18 chances.
The Blue Jays opened the scoring in the first when Melky Cabrera scored on a wild pitch, but the Orioles tied it in the fifth after Chris Davis reached on second baseman Emilio Bonifacio's error and later scored on Travis Ishikawa's single.
Izturis put the Blue Jays back in front by homering on the first pitch of the fifth, his fifth.
Baltimore left the potential tying run stranded at third base in the seventh but knotted it at 2 in the eighth on Teagarden's one-out homer.
The Orioles have homered in 10 consecutive games, their longest streak of the season.
Blue Jays starter Chien-Ming Wang left to a standing ovation after giving up one run and five hits in 6 1-3 innings. The right-hander, who walked none and struck out two, has a 2.61 ERA in three starts with Toronto.
"We just didn't do a whole lot off of Wang," Showalter said. "He creates a great angle. His sinker has got some lateral movement and some downward movement."
NOTES: Bautista is one home run away from 200 for his career. ... Blue Jays RHP Kyle Drabek (elbow surgery) is set to begin a minor league rehabilitation assignment with Class-A Dunedin on Saturday. ... Orioles C Matt Wieters got the day off, while Chris Davis started at DH. He doubled and scored a run, but struck out to end the game. ... Baltimore RHP Freddy Garcia is expected to start Sunday's series finale against RHP Josh Johnson, meaning LHP Zach Britton will start for the Orioles against Cleveland on Monday.