Young (3-0) allowed three hits, while striking out three and walking none. The tall right-hander needed just 96 pitches, setting down the lineup in order in five of his eight innings.
It is the first time Young has thrown at least eight innings since he tossed a complete game for the San Diego Padres in 2008. Young didn't play last season and pitched sparingly from 2009-12.
Fernando Rodney pitched around a two-out single in the ninth inning to record his 11th save in 12 attempts.
Smoak gave the Mariners a 2-1 lead in the fourth, hitting a no-doubter into the seats in right field for a two-run home run.
Ackley added a solo shot to right in the sixth inning off Royals starter Yordano Ventura.
Ventura (2-2) allowed three runs in 6 1-3 innings. The right-hander issued a season-high four walks, while notching a season-low three strikeouts.
Mariners right fielder Michael Saunders hurt himself when his foot slid in the grass near the right-field line while he was chasing a ball hit by Mike Moustakas in the top of the third inning. Saunders fell to the ground and the ball bounced over him, allowing Moustakas to reach third with a triple.
The Royals took advantage of the opportunity as Alcides Escobar followed with a sacrifice fly to left to give Kansas City a 1-0 lead.
Saunders left the game after the inning and was diagnosed with a hyperextended left knee. He is considered day to day.
The four hits tied a season-low for the Royals, who have struggled to find power during their time in Seattle. Of its 23 hits in three games thus far in the series, Kansas City has just one extra-base hit.
Royals manager Ned Yost challenged a ruling that Robinson Cano was safe at second in the seventh trying to advance on a wild pitch. The call was reversed after a delay of 2 minutes, 27 seconds.
NOTES: Sunday's series finale will pit Seattle LHP Roenis Elias against Kansas City RHP Jeremy Guthrie. ... Mariners rookie James Jones hit in the leadoff spot for the first time in his career. Manager Lloyd McClendon said Jones, who hit .306 in the minors from the top spot in the lineup, is a ''prototypical leadoff guy.'' ... Home plate umpire Scott Barry left Saturday's game following the third inning after appearing to take a pitch off his right hand. Crew chief Jeff Nelson took over behind the plate and the game finished with three umpires.