The Pirates activated O'Hearn (quadriceps) from the 10-day injured list Friday.
Sidelined since late July with a left quadriceps strain, O'Hearn has been cleared to return after going 1-for-7 with one double and a 1:2 BB:K in two rehab games with Triple-A Indianapolis. The 33-year-old has authored a .270/.334/.454 batting line with 17 home runs over 96 contests this season. Manager Don Kelly said Friday that O'Hearn will likely be limited to first base and designated hitter down the stretch so as not to risk aggravating his quad issue in the outfield, per Aiden Stepansky of MLB.com. O'Hearn is not in the lineup Friday against Cubs lefty Shota Imanaga.