Cuthbert drove in two runs off Miley, and right-hander Edinson Volquez tossed a quality start as the Royals held off the Mariners for a 5-3 win on Saturday afternoon at Kauffman Stadium.
"That's a big win for us," Royals manager Ned Yost said. "Nice to see us get some offense going."
Royals catcher Salvador Perez, the leading vote-getter for the All-Star Game presented by MasterCard, homered, his 14th. Perez also picked the potential tying run off first base in the eighth inning when he nailed Kyle Seager -- it was Perez's Major League-leading 18th pickoff since 2011.
"That was just a huge play for us at the time," Yost said.
Volquez threw 91 pitches as he gave up six hits and three runs while walking one and striking out three. Kelvin Herrera worked a 1-2-3 ninth for his first save since 2013.
"I just wanted to challenge them," said Volquez, who threw 68 of his 91 pitches for strikes. "I thought I did a good job today."
Herrera even correctly remembered his last save.
"Against the Twins, right?" Herrera asked. "It was good. I just thought about getting ahead of them and I did."
After a shaky start, Miley, who gave up three runs in the second, lasted 5 1/3 innings and gave up 10 hits and four runs. Seager hit a three-run homer for the Mariners, his 18th.
MOMENTS THAT MATTERED Cheslor to the rescue: Cuthbert, who had doubled in a run in the second, came through in the sixth. Paulo Orlando had reached on a leadoff infield single, and Brett Eibner waked. Alcides Escobar laid down a poor bunt, and Orlando was forced at third base. But Cuthbert drove a single to left-center that put the Royals up 4-3 and chased Miley from the game.
"That was actually a pretty good bunt," Yost said. "They made a good play. But then Cheslor came through with a big hit."
Making amends: In the second inning with two runners in scoring position, Escobar hit a ground ball to Seager, who appeared to have a chance to get Perez out at home. Seager fumbled the ball and had to throw to first, as the run scored. Seager made up for his miscue by belting a game-tying three-run homer off Volquez in the fourth.
"He hit it a little off to the left, but I was going to go home on that ball," Seager said. "It stuck in my glove a little longer than I had hopped and kind of popped out on me. [I] wasn't able to get him."
Seager's 18th homer extended his hitting streak to 12 games.
"Down 0-2, you're just in battle mode," Seager said. "Thankfully, I got a pitch that probably caught a little more plate than he wanted."
Triple-double: The Royals jumped to a 3-0 lead in the second inning off Miley. Perez led off with a walk, and one out later, Eibner stroked a double to left-center. Escobar plated one run with a groundout. Then, Cuthbert doubled in another run to make it 2-0. Rookie Whit Merrifield doubled to right-center and it was 3-0.
A missed opportunity: In the fifth, the Mariners let a run-scoring opportunity slip away. With runners on the corners and one out in a tie game, Leonys Martin could not execute on a couple of sacrifice attempts. Later in the at-bat, Ketel Marte was caught in a rundown between first and second, making the second out of the inning. Martin drew a walk, but Seth Smith struck out to end the inning.
"We talked about it a little bit. [Marte is] a base-stealing threat. He needs to go steal that base," manager Scott Servais said. "If you don't get a good jump, you shut it down.
"You can't give away outs. It'll catch up to you."
LEE'S LINGERING INJURY
After getting the start at DH, Mariners regular first baseman Dae-Ho Lee was replaced by pinch-hitter Franklin Gutierrez in the sixth inning, just one day after Lee missed Friday's game with soreness in his right hand. The diagnosis for Lee is a hand contusion, which is expected to keep him out until after the All-Star break, according to Servais. More >
"It's just sore. Yesterday was a rest day," Lee said through interpreter D.J. Park. "I jammed it [over time]. That's what happened."
UPON FURTHER REVIEW
In the eighth inning with runners on the corners and one out, Perez recorded his first pickoff of the season, as he threw out Seager at first base. The umpires reviewed the play and the call was ruled as stands. Gutierrez then flied out to center to end the inning and the Mariners couldn't capitalize with runners on the corners and one out for the second time in the game.
"You can't get picked off in that situation," Seager said. "[Perez] is pretty special back there, but I obviously got off too far."
WHAT'S NEXT Mariners: Left-hander Mike Montgomery (2-3, 2.15 ERA) will take the mound on Sunday at 11:15 a.m. PT for the final game of the series at Kauffman Stadium. Montgomery threw a shutout against the Royals last year, striking out 10 in a 7-0 win on June 23.
Royals: Right-hander Dillon Gee (3-2, 4.05) will get the ball in the team's final game before the All-Star break at 1:15 p.m CT. Gee will make his first start since May 31, when he gave up nine hits and four earned runs in a 10-5 win over the Rays.