Disclosed are a robot system and a control method thereof. The robot system includes a first server, a first robot which is registered on the first server and which delivers an item to a user according to information received from the first server, a second robot which is configured to interoperate with the first robot and which receives the item from the first robot, and a second server on which the second robot is registered and which operates the second robot. The method for controlling the robot system includes transmitting customer information to the first robot by means of the first server, authenticating the first server, by means of the second robot, so as to allow the first server to access the second robot, and requesting the first robot, by means of the first server, to couple with the second robot so as to allow the first robot to operate in correspondence with operation of the second robot.