But Kinney didn't love the execution of the sinker he tried throwing away from the Royals' cleanup hitter, as instead it ran over the plate and wound up in the wheelhouse of a guy who knows what to do with a mistake.
"I just got a good pitch to hit and didn't miss it there at the end," Butler said after hitting his 18th home run of the season and second walk-off of his career.
Kinney was pitching because Brandon League and Lucas Luetge were unavailable due to recent usage. League threw on Sunday and Monday and also had warmed up extensively on Tuesday. Luetge, as well as Shawn Kelley, had pitched Monday and Tuesday.
Closer Tom Wilhelmsen was being held in reserve for a save situation as always in a road-game scenario, leaving Kinney in a surprising situation for a guy who'd pitched two innings in three prior appearances for Seattle.
"He was the guy," manager Eric Wedge said. "We had League and Luetge down. We were going to stay away from both those guys. Josh has been throwing the ball well in the short period of time he's been up here and did a nice job getting out of the inning before.
"It just looked like a pitch that was up. Butler's a pretty good hitter and he got to it."
Most of Kinney's career has been spent in the Minors, but he's been around and pitched once against Butler last year while with the White Sox.
"I know he's their dangerous guy in the lineup," said Kinney. "We had a plan, I felt good out there. I had command of my pitches. I actually felt real good, but that's what happens when you miss your spot to that guy and he did exactly what he's supposed to do. Sometimes it stinks, but you just have to say, 'Hey, he got me.' Maybe I'll get him tomorrow."
Even in the losing effort, the Mariners' bats continued to warm up in the Midwest heat on a 103-degree evening. Kyle Seager and Casper Wells hit home runs for a Seattle club that racked up 14 hits in its ongoing road surge and now has seven long balls in the first three games of the four-game series.
Mariners right-hander Kevin Millwood couldn't take advantage of the latest offensive outburst as he wound up with a no-decision after allowing seven runs and 10 hits in a five-inning struggle. He's now 3-7 with a 4.15 ERA.
Millwood had pitched much better than his record this year, with poor run support contributing to a string of nine straight starts now without a victory. Seattle had totaled just 21 runs in the veteran's last eight outings, during which he'd posted a solid 3.70 ERA with no wins in return.
This time the Mariners gave him some help, but the 37-year-old couldn't cash in. He's 0-3 with six no-decisions since his last win on May 23.
Seager opened the scoring with a solo shot down the right-field line in the second for a 1-0 lead and added an RBI double in the seventh that tied the game at 7. The young third baseman now has 11 home runs for the season and a team-leading 58 RBIs.
Wells ripped a two-run shot to left field, a 397-foot blast that tied the game at 3-3 in the fourth. The left fielder went 3-for-5 has hit .301 with five home runs and 18 RBIs in 26 games since being recalled from Triple-A Tacoma on June 13.
Rookie catcher Jesus Montero continued his own recent surge with a 2-for-5 night that included a two-run single in the seventh, while Ichiro had three hits and scored twice.
The Mariners missed a golden opportunity to break the 7-7 tie in the top of the eighth when Brendan Ryan tripled, but was thrown out at home on a ground out to second by Dustin Ackley on a close play where his foot appeared to come up and over the plate just as the tag was applied by catcher Brayan Pena.
"[Home-plate umpire Jim Joyce] said he didn't touch the plate," Wedge said. "Hey, we're going for it. We were trying to win the game on the road right there. When the kid [second baseman Chris Getz] threw the ball in the dirt, I thought we had a chance. But their catcher made a heckuva play right there to pick it and throw the tag on."
Ryan didn't know his foot went over the plate until told afterward.
"We're going on contact there and they're just going to have to make a play," he said. "The ball was a step to his right and I didn't really see the throw or anything, I was just trying to get to home as quick as I could. It was a close play, but ..."
Instead, the game went to the ninth still deadlocked, until Butler settled the score with one swing as his 395-foot drive cleared the fence in left-center.