This paper introduces a design scheme for a cascaded lightweight integrated servo. By adopting a parallel adaptive layout of a brushless moter and transmission mechanism, as well as an integrated scheme combining driving and actuation components, the proposed design employs an “ARM+power drive module+DC brushless moter” control architecture. Through compact circle layout and structural optimization, the mechanism’s weight is effectively reduced by 8%, and energy consumption is minimized. To decrease the radial dimensions of the servo mechanism, a novel compact reducer structure is proposed, utilizing a central shaft to connect transition gears and achieve integrated shaft support. Simulation and experimental results validate the design and further analyze the impact of command delay on the performance of the integrated master-slave servo mechanism. A comparative analysis of integrated versus modularized mechanisms is also provided.