The Royals activated Schreiber (knee) from the 15-day injured list Monday.
Schreiber will rejoin the Royals bullpen after a three-week stay on the injured list due to right knee soreness. The 30-year-old has a 4.14 ERA and a 30:13 K:BB across 37 innings for the Royals this season. Carlos Hernandez was optioned to Triple-A Omaha in a corresponding move.