Miniaturized, multifunctional, and economical on-orbit service satellites have been increasingly used with the continuous increase of space exploration missions. In this paper, an innovative deployable manipulator is designed, named Cubot, which can be stowed in 1 U-sized (10 cm×10 cm×10 cm) space. With CubeSat as the carrier, the deployable Cubot aims to achieve a variety of on-orbit operation tasks including space debris removal and space station on-orbit maintenance, for future on-orbit servicing, assembly, and manufacturing (OSAM). A kinematics modeling method of a space manipulator with passive joints is proposed, and the motion equation of the manipulator is derived. Considered the elastic potential energy stored in the passive joint during deployment, the momentum change of Cubot is simulated and analyzed. As the main forced element, the end effector is analyzed using FEA. Dynamic stress response with respect to the force distribution and the clamping angle is analyzed to evaluate mechanical performances of the end-effector component. Deployment tests are conducted to verify the feasibility of Cubot based on a principled prototype, which aims to provide engineering and practical experience for the development of this field.