This is the emotional moment a dad was reunited with his adoptive daughter after he donated part of his liver to save her life.

Peter McKay, 38, was moved to tears as he watched over baby Darcy hours after a portion of his vital organ was transplanted into the sick tot.

Darcy had been battling progressive familial intrahepatic cholestasis type 2, or PFIC2, which prevents liver cells from flushing out bile, forcing it into the bloodstream.