A grip strengthener with therapy ball includes a resilient pad and ball. The pad is flat and has at least one side surface, a top surface, a bottom surface, a ball mount and a finger slit. The ball mount is defined through the pad and has an inner edge. The finger slit is defined in the top surface of the pad between the ball mount and one of the at least one side surface. The ball is mounted detachably in the ball mount of the pad and has an outer surface, a mounting groove, a top side and a bottom side. The mounting groove is defined around the outer surface of the ball and engages the inner edge of the ball mount in the pad. The top side and the bottom side respectively protrude the top surface and the bottom surface of the pad.