Miguel Olivo added a solo home run for the Mariners, who have won two straight.
Kevin Millwood (6-12) allowed two runs on two hits and a walk over five innings before leaving with stiffness in his shoulder, while Tom Wilhelmsen tossed a scoreless ninth inning to record his 26th save of the year.
"We'll see how he feels when he comes in here the next couple of days," Mariners manager Eric Wedge said if Millwood will miss his next start.
Ricky Romero (8-14) surrendered all three runs on eight hits and four walks through four-plus innings to remain winless in 14 starts. He is 0-13 over that span and has not recorded a win since June 22.
"We're going to continue to work with him," Toronto manager John Farrell said. "We're going to continue to finish this year on a positive note and that is our intent going forward."
Edwin Encarnacion's two-run homer accounted for Toronto's offense as the Blue Jays dropped their second consecutive contest on the heels of a four-game win streak.
Seattle struck first in the second inning with Olivo's solo shot just over the left-center field wall.
The Mariners then added a pair of runs in the fourth inning when Brendan Ryan worked a two-out walk and advanced to third on Dustin Ackley's ground-rule double to left field. They both came home on Gutierrez's base hit through the right side of the infield.
Toronto, meanwhile, did not have a baserunner until Colby Rasmus walked with one out in the bottom of the fourth. Encarnacion followed with a blast into the second deck in left field to bring the Blue Jays within 3-2.
Seattle failed to add to its lead by leaving the bases loaded in the fifth inning and stranding a runner on third in the ninth, but an insurance run proved unnecessary as the Blue Jays failed to advance a runner past first base after the fourth inning.
Olivo hit his 10th home run of the season, while Encarnacion recorded his 39th ... Mariners designated hitter Jesus Montero went 0-for-4 to snap a career- high nine-game hit streak ... Millwood improved to 3-8 in 14 career starts against Toronto ... Romero fell to 1-3 in eight starts against the Mariners ... Seattle leads the season series between the teams, 6-2 ... The Mariners hit 1-for-11 with runners in scoring position and left 12 men on base ... Toronto did not have an at-bat with a runner in scoring position and stranded two runners.
09/13 02:18:42 ET