Human upper-limb movement is produced through the antagonistic action of tendons and is controlled in a joint space-oriented manner. Inspired by this functionality, a fully decoupled tendon-driven humanoid arm (FDTDH-Arm) is proposed in this video, in which joint space decoupling is achieved at the mechanical level via humanoid antagonistic actuation and joint regulation rather than complex modeling-based compensation. To characterize the motion behavior introduced by rolling constraints, joint-level and whole-arm kinematic models are established. A prototype of the proposed arm is developed and experimentally validated. The results demonstrate effective mechanical joint space decoupling, passive joint stiffness of the same order of magnitude as that reported for the human upper limb, a mean positioning error of 0.40 mm, and rapid whole-arm motion with a maximum end effector velocity of 3.62 m/s. This video provides a mechanical implementation and biomimetic solution for humanoid manipulation in human-interactive environments.