In the eighth inning, Rodriguez blasted reliever Carlos Hernandez's (1-8) first pitch 438 feet beyond the left-field bullpen for a three-run home run, his 20th, giving the Mariners a 5-4 lead.
Rodriguez opened the scoring with a two-out RBI hit in the second inning, and also broke a 1-all tie with a sixth-inning double. His five hits set a career high and his five RBIs matched another career best.
Rodriguez went 12-for-21 with 11 RBIs during the four games in Kansas City.
Cal Raleigh's pinch-hit solo homer in the ninth capped the scoring as the Mariners took three of four games to win the series. Seattle has won 11 of 14.
Kansas City's Nelson Velazquez tied the game with a two-out solo shot in the fourth, his high drive to center field barely clearing Rodriguez's leaping grasp. It was the fourth home run for Velazquez in his last six games, and it broke a string of 16 scoreless frames by Mariners starter George Kirby.
Kirby allowed four runs on eight hits in six innings, striking out two. Isaiah Campbell (3-0) allowed one hit in an inning of relief, while Matt Brash earned his fourth save — and second in two days — with a perfect ninth.
Kansas City took a 4-2 lead in the bottom of the sixth as five consecutive hitters reached safely. Michael Massey's RBI single tied the game 2-2 before MJ Melendez delivered an RBI double and Freddy Fermin added a sacrifice fly.
Over four innings, Royals starter Angel Zerpa allowed a run on five hits, two walks and two hit batters, striking out six. The Mariners had multiple baserunners in five of the first six innings, but they left eight on base while batting 1-for-8 with runners in scoring position before Rodriguez's RBI double in the sixth.
Maikel Garcia's hitting streak ended at 18 games, a club record for rookies, as the Royals have lost nine of 12.
—Field Level Media