The optimal design and the experimental validation of a cable-driven parallel robot is discussed in this paper. This novel device is intended for assisting therapists in the rehabilitation of the head–neck joint. First, the motion of the head–neck joint was recorded by means of a Qualisys motion-capture system. The collected data was then analyzed in order to obtain the range of motion of the head and to identify some prescribed trajectories. A novel end-effector design was proposed to reduce the degrees of freedom needed to perform the desired head motion. The best design was found through an optimization problem where the cable tensions are minimized and the robot dexterity is maximized within its workspace. The objective of this optimization was to find the optimal actuator positions while satisfying a set of constraints. A prototype was proposed and experimental tests were conducted to validate the robot performance. In particular, a comparison between the actual trajectories and the desired ones was performed. The experimental test showed promising results.