The Royals activated Massey from the 7-day concussion injured list Wednesday.
Massey was injured Aug. 25 against Toronto when he fell down making a throw to first base and missed the past six games. The 28-year-old is slashing .276/.310/.444 with 11 home runs, 44 RBI, 46 runs scored, two stolen bases and a 19:62 BB:K across 366 trips to the plate this season.