Abstract: The dexterous hand mimics the functions of human hands through electromechanical systems. However, how to layout the high degrees-of-freedom (DoFs) in limited space and address the mechanical coupling and maintenance problems is challenging for the design and implementation of robotic dexterous hands. Therefore, a fully actuated, three-fingered dexterous hand driven by a cable-driven mechanism is developed. By optimizing the cable arrangement and joint structure, the layout and mechanical decoupling of all 11 DoFs are achieved, effectively reducing the control complexity. This design also intends to solve the high-DoFs layout difficulties and severe mechanical coupling problem. In addition, a cable tensioning device is designed to adapt to the cable length changes, guarantee the tension of cables, and decrease the maintenance cost and difficulty. Finally, the designed dexterous hand demonstrates a high-DoFs structure similar to that of a human three-fingered hand, while keeping the fingers slender, with cross-sectional dimensions close to those of an adult male. The grasping performance of the dexterous hand is tested, the significance of the cable tensioning mechanism on the high-DoFs dexterous hand is verified by physical experiments, as well as the decoupling effect of the proposed hardware decoupling scheme.