Recalled from Triple A Norfolk to face the Blue Jays, Britton (5-1) allowed four hits and improved to 4-0 with a 0.94 ERA in four starts since his last loss on Aug. 1 against New York. The lefthander struck out eight and walked two, one intentional.
Kevin Gregg worked the eighth and Zach Phillips finished for the Orioles, who have won three straight and 21 of 29.
Struggling Toronto was held scoreless for the second straight game at home and has dropped four in a row.
Reynolds hit his 17th homer off Carlos Villanueva in the fifth. It also was his fifth homer in five games.
Nate McLouth added a sacrifice fly in the sixth, and the Orioles pulled away with a three-run seventh. Robert Andino chased Villanueva with a sacrifice fly, Aaron Loup's balk scored Manny Machado and J.J. Hardy singled in Nick Markakis.
Villanueva (7-5) lost for the fifth time in seven starts, allowing a season-high six runs and seven hits in 6 2/3 innings.
Baltimore added five more runs against Loup and Chad Beck in a 10-batter seventh. Chris Davis hit an RBI double, Reynolds and Machado each singled in a run, Markakis tacked on an RBI double and McLouth capped the outburst with an RBI single.
Mechanical troubles with the retractable roof at Rogers Centre left the field slippery and damp during the middle innings as rain fell inside the stadium. The roof finally closed in the bottom of the seventh.
Also, Orioles righthander Jason Hammel is expected to come off the 15-day disabled list to start Thursday in the opener of a crucial four-game series against the Yankees in Baltimore. Jim Thome, out since July 28 with a herniated disk in his neck, is feeling better and is scheduled to see a doctor on Thursday, Showalter said.
In other games
* At St. Petersburg, Fla., Evan Longoria hit a go-ahead homer and the Tampa Bay Rays beat New York, 5-2, to drop the struggling Yankees into a tie for first place in the AL East. The Yankees fell into a tie for the division lead with the surging Orioles after sitting atop the standings by themselves for 84 consecutive days - New York's longest streak since 2004.
Desmond Jennings and B.J. Upton also homered for the third-place Rays, who pulled within 1 1/2 games of the Orioles and Yankees. Tampa Bay trailed by a season-high 10 1/2 games at the end of play on July 18. Longoria hit a two-run shot off Freddy Garcia (7-6), wiping out a 2-1 deficit in the third inning.
* At Chicago, Chris Parmelee homered to cap a 10-run fifth inning and the Minnesota Twins routed the White Sox, 18-9. The Twins also batted around in a seven-run second, but first-place Chicago remained one game ahead of Detroit in the AL Central. The Tigers lost 3-2 to Cleveland. Minnesota pecked away methodically with 17 hits - only three went for extra bases.
* At Detroit, Justin Masterson pitched six solid innings, and the Cleveland Indians beat Detroit, 3-2, for their second straight victory over the playoff-chasing Tigers.
The Tigers missed another opportunity against a struggling team. The Indians had lost 29 of 35 before taking the first two games of this series.
* At Kansas City, Jeremy Guthrie pitched seven strong innings and the Royals got home runs from Alex Gordon and Johnny Giavotella in a 6-3 victory over the Texas Rangers. Gordon broke a 2-all tie in the fifth with a two-run shot off Matt Harrison (15-9), the third home run he has allowed to a lefthanded hitter this season.