The invention discloses a gripper for a mobile robot, a robot arm and the mobile robot. The gripper comprises a bottom plate. The bottom plate and a mechanical arm of the mobile robot are fixed, and the bottom plate rotates along with rotation of the mechanical arm. At least one mechanical finger is fixed to the bottom plate, and the mechanical fingers rotate under rotation of the mechanical arm so as to stir a door handle or a valve handle or a valve hand wheel. A finger elastic sheet with a protrusion is arranged on the inner side of each mechanical finger, the mechanical fingers can penetrate the door handle through the elastic function of the finger elastic sheets, the protrusions are used for fixing and limiting the door handle, the door handle is opened better, and meanwhile the fixing manner of the elastic sheets can guarantee elastic sheet fixing and can also achieve the telescopic effect.