On January 10, 2015, Zobrist was traded to the Oakland Athletics with teammate Yunel Escobar in exchange for John Jaso, Daniel Robertson, and Boog Powell. On opening day with the Athletics, Zobrist hit a two-run homer in his first at-bat. On April 25, 2015, it was revealed that Zobrist had a torn medial meniscus in his left knee, putting him on the 15-day disabled list. The knee required surgery, keeping Zobrist out of action for 4–6 weeks.
On July 28, 2015, Zobrist was traded to the Kansas City Royals for Sean Manaea and Aaron Brooks. He played 59 games in the regular season for Kansas City and finished with a batting average of .284, with 7 home runs, 37 runs scored, and 23 RBIs.
The Royals won the AL Central Division and played the Houston Astros for the ALDS with Zobrist starting in all five games. The Royals advanced to the World Series after defeating the Toronto Blue Jays in six games to become the American League Champions. The Royals won the 2015 World Series after defeating the New York Mets in four of the five games played. Zobrist played second base and batted second in every game of the 2015 Royals postseason. He hit .303 in the 2015 postseason with 66 at bats, 15 runs scored, 20 hits, 2 home runs, and 6 RBIs.
On December 8, 2015, Zobrist agreed to a four-year, $56 million contract with the Chicago Cubs. The signing reunited him with Joe Maddon, his manager when he was a member of the Tampa Bay Rays. In 2016, he batted .272/.386/.446 and led the major leagues in walks-per-strikeout at 1.17.