Force–torque sensors are used in many and different domains (i.e., space, medicine, biology, etc.). Design solutions of force–torque sensors can be conceived by using many types of connections or components; however, there are only a few sensors designed using cable-driven systems. This could be related to many reasons, one of which being that cables are able only to pull and not push. In this paper, a new cable-driven model for under-actuated force–torque sensing mechanisms is proposed, simulated, and tested, underlining the novelty of using cables for force–torque sensing. Analytical formulations, simulations, and physical implementations are presented in this paper. Results confirm that the new proposed model can be used for force–torque sensing mechanisms in micro- and macro- applications where under-actuation is a fundamental requirement, as in robotic surgery. The proposed model and mechanism can be used in the design of sensors and actuators. The innovative model is validated with two different test benches, opening new challenges in the design and development of under-actuated force–torque transducers.