<p>Aiming at the innovative design requirements of rehabilitation robots with multiple kinematically coupled components and the current absence of systematic processes in the design of such mechanisms, this paper presents the concept of a multi-output component mechanism (MOCM). A classification methodology for the MOCM is proposed based on the operational coupling between the actuators and the output components within closed-loop mechanisms. Building on the classification results, a design methodology for a kinematically coupled MOCM (KCMOCM) is proposed based on the actuation distribution within the closed-loop sub-mechanisms. First, the number and relative kinematic characteristics of the output components are determined based on the application environment of the mechanism. These components are then grouped and classified according to motion similarity principles, followed by the design of closed-loop sub-mechanisms with actuators for each group, ultimately forming a complete KCMOCM. Taking the sit–stand–lie-bed mechanism in a spinal cord injury lower-limb rehabilitation robot as an example, this study comprehensively considers the multi-posture transition task requirements and spatial constraint characteristics of lower-limb rehabilitation training to design the mechanism. By applying the mechanism design methodology, six practical novel configurations are developed with established evaluation criteria, and kinematic analysis and experimental validation are performed on the optimized configuration. The results demonstrate that the optimized configuration satisfies the multi-posture rehabilitation training requirements for lower limbs. This validates the efficacy of the design methodology. Furthermore, the scalability of the design methodology is validated through the development of a robotic finger rehabilitation mechanism.</p>