The Guardians edged the Mariners 6-3 to win their series from Progressive Field.
Andres Gimenez blasted a two-run homer and Will Brennan also went deep with a solo shot.
Logan Allen earned the win as Cleveland won its second straight game.
The Guardians are still first in the AL Central at 46-and-26 and will host the Blue Jays for the first of three games tonight.