Jones hit two homers, extending his hitting streak to 20 games, and Chris Davis added a two-run drive, but it wasn't enough for Baltimore. The Orioles have lost four straight and seven of nine but remain tied with Tampa Bay atop the American League East.
Jones hit a leadoff home run to right in the second and a two-run shot to left in the ninth, his 15th and 16th homers. It was his first multihomer game this season and the second of his career.
Catcher Matt Wieters, who picked up his first career ejection, acknowledged that Baltimore has hit a rough patch.
"It's definitely been a frustrating couple of games," said Wieters, who was tossed for arguing with plate umpire Doug Eddings in the bottom of the fifth. Wieters was replaced by Ronny Paulino.
Lawrie also made a spectacular sliding catch in foul territory for the second out of the ninth inning, helping the Blue Jays out of a late jam, but it was his hitting that caught the eye of manager John Farrell.
"The biggest thing for me was I thought he stayed behind the baseball," Farrell said. "That's the first time in a while he's driven some balls, some fastballs that were up and away from him driven the other way."
Romero (6-1) improved to 7-1 with a 2.43 ERA in his past nine starts against the Orioles. The left-hander allowed four runs and six hits in six innings to win for the second time in five starts.
After walking a career-high seven in his previous outing, a May 23 game at Tampa Bay, Romero walked just one against Baltimore, while striking out seven.
"I don't care what I've heard about his last start or his previous 40 starts," Jones said of Romero. "The guy is nasty every time he takes the mound."
Jones got the Orioles started with a leadoff drive to right in the second, his 15th, but the Blue Jays responded with two in the third against Baltimore right-hander Jake Arrieta (2-6).
Lawrie and Cooper opened the inning with singles, and Davis followed with a bunt. Lawrie scored when Arrieta threw wildly to first, with the other runners ending up at second and third.
"I had a pretty rough grip on the ball and made a bad throw," Arrieta said. "That right there put me in a tough spot early in the game. I can only blame myself for that."
One out later, a second run scored on Yunel Escobar's groundout.
Lawrie hit a two-run double in the fourth, and Davis added an RBI single, putting Toronto up 5-1.
The Blue Jays added three more in the fifth, when Lawrie, Cooper and Davis hit consecutive RBI singles off reliever Miguel Gonzalez, who was making his major league debut.
Wieters, his temper rising after several questionable calls in the inning, didn't hold back from letting Eddings know how he felt, taking off his mask and yelling in the face of the umpire after getting thrown out.
"He gave me plenty of rope, and that's something that's clear, you can't argue balls and strikes," Wieters said. "It was something where I knew I might be going there but I still had to say my peace."
Arrieta allowed seven runs, six earned, and six hits in 4 1/3 innings, extending his winless streak to five starts. Arrieta, who has won just once in his past 10 outings, walked three and struck out five.
Baltimore chased Romero by scoring three runs in the sixth. Jones singled, moved to third on Paulino's double and scored on Mark Reynolds' groundout. Davis followed with a two-run homer to left, his ninth.
The Orioles loaded the bases against Frasor in the seventh, but Paulino ended the inning by grounding out.
Baltimore put runners at second and third in the eighth but Cordero struck out Robert Andino to end the threat.
Orioles manager Buck Showalter said OF Nick Markakis "tweaked" his right wrist on a swing in the ninth. Markakis will be re-evaluated Wednesday. ... The Orioles activated OF Endy Chavez off the 15-day DL and promoted Gonzalez from Triple-A Norfolk, with OF Xavier Avery and RHP Tommy Hunter optioned to Norfolk. ... Toronto recalled INF Mike McCoy from Triple-A Las Vegas and optioned OF Eric Thames to Las Vegas. ... Orioles OF Nolan Reimold (neck) is feeling better after receiving a second epidural last week and is ready to report to extended spring training in Florida to begin his rehab.