The Royals acquired outfielder Jonny Gomes from the Braves on Monday.
Atlanta will receive minor league shortstop Luis Valenzuela in return for the veteran Gomes.
Valenzuela will be assigned to the Rome Braves, Atlanta's Class A affiliate.
In 83 games this season, Gomes, 34, is hitting .223 with seven home runs and 22 RBIs.
During August, however, Gomes posted an .878 OPS against lefthanded pitchers.
Kansas City is the seventh team Gomes has played for in his thirteen Major League seasons.
Gomes was a World Series champion with the Boston Red Sox in 2013, and has played in four of the last five postseasons.
In January, Gomes agreed to a 1-year, $4 million contract with the Braves.
- Kayla Lombardo