Jose Abreu extended his hitting streak to 14 games with an RBI single as the White Sox posted their first shutout of the season in their 83rd game and won three straight for the first time since May 26-28 against Cleveland.
"It starts off with Q," manager Robin Ventura said. "He threw great. He was attacking the zone. If he can get ahead and stay there, and mix speeds like he did today, he's tough."
Quintana (5-7) allowed three hits in seven innings, improving to 4-1 with a 1.80 ERA in six starts against the Blue Jays. He walked two and struck out seven.
"Today the big pitch was the ability to throw effective off speed pitches early to get ahead," catcher Tyler Flowers said. "His slider-slurve thing, he had a really good feel for that."
"A nice win all the way around," Ventura said as his team ended a season-long 11-game road trip on a high after losing seven of the first eight.
The AL East-leading Blue Jays were blanked for the fifth time this season. Four of those have come in the past 22 games.
"I thought we were definitely flat today," Blue Jays manager John Gibbons said. "I haven't seen that all year."
Toronto went 12-15 in June after going 21-9 in May.
"Since our big streak, we've cooled off quite a bit," Gibbons said. "We need to get going."
Facing his former team for the second time, Blue Jays left-hander Mark Buehrle (10-5) lost for the fourth time in five starts, allowing two runs and six hits in eight innings. He walked two and struck out five.
"You know what he has, it just seems like it's tough to line him up like you want to," friend and former teammate Paul Konerko said of Buehrle.
Buehrle lost four straight decisions for first time since dropping four in a row for Miami from June 1-19, 2012. He has not won since June 1 against Kansas City.
Buehrle, who spent the first 11 seasons of his career with Chicago, beat the White Sox in Toronto on April 15, 2013.
Gordon Beckham hit a two-out double off Buehrle in the third and scored when Abreu followed with a first-pitch single to left.
Sierra, who began the season with Toronto but was designated for assignment on May 1, doubled Chicago's lead with a one-out blast in the fourth.
"I pretty much teed one up for him and that's what he's supposed to do with it," Buehrle said.
Toronto's Jose Reyes hit a one-out double in the eighth and, one out later, Edwin Encarnacion walked. Jose Bautista, who hadn't played since leaving last Sunday's game at Cincinnati with a strained left hamstring, pinch hit for Dioner Navarro, but grounded out.
Flowers capped the scoring with a two-run single off former White Sox closer Sergio Santos in the ninth.
Chicago won three straight road games for the first time since May 4-6, when they beat Cleveland once and the Cubs twice. ... Bautista ran in the outfield before the game and said his leg was still sore. He hopes to be able to DH Tuesday. ... Toronto LH Brett Cecil (groin) will begin a rehab assignment with Triple-A Buffalo on Monday. ... The Blue Jays are off Monday before opening a two-game series against Milwaukee on Tuesday. Brewers RH Marco Estrada (7-4) faces Toronto RH Drew Hutchison (5-6). ... The White Sox return home to begin a three-game series against the Los Angeles Angels on Monday. Angels RHP Garrett Richards (8-2) faces Chicago RHP Hector Noesi (2-5).