The Diamondbacks reinstated Castro (shoulder) from the 15-day injured list Thursday.
Castro pitched two innings in his final rehab appearance Saturday and gave up no runs on one hit with a walk and a strikeout. The right-hander is now set to make his return after he landed on the injured list due to right shoulder inflammation in late April. In a corresponding move, Slade Cecconi was optioned to Triple-A Reno.