The Phillies activated Kerkering (hamstring) from the 15-day injured list Tuesday, Todd Zolecki of MLB.com reports.
Kerkering got a late start to the season after straining his right hamstring during spring training, but he's ready to roll after four rehab appearances. The 25-year-old will settle into a setup role for the Phillies, though he could be eased back into high-leverage situations following the layoff.