Slowey (10-5) allowed only three hits, didn't issue a walk and struck out five to log his first eight-inning start since April 20. He allowed only one runner to reach as far as third in his 103-pitch gem.
Young tripled home a run during a three-run first inning and drove in another with an RBI single in the eighth. He hit .442 for the month of July (46-for-104) with 30 RBI.
Joe Mauer went 3-for-4 with a run batted in and two runs scored for Minnesota, which won its seventh straight game and ninth in 10 outings to pull within a half-game of Chicago atop the American League Central.
Seattle starter Felix Hernandez (7-8) pitched well in defeat, yielding three runs on seven hits over seven innings.
With the loss, the Mariners concluded the worst month in their franchise history, going 6-22 in July.