This paper presents the conceptual and functional design of an innovative cable-driven hip exoskeleton, conceived with a new sustainable actuation approach. The exoskeleton is designed within the framework of the REBALANCE* project, which aims at reducing falls, related healthcare, and associated costs in the older population. The exoskeleton supports the thighs to aid the control of the hip joint. A key feature of the exoskeleton is in the concomitant control of the human legs’ flexion, extension, and abduction. The cable-driven mechanism of the exoskeleton ensures sustainability. This mechanism reduces up to 50% of the power supply, weight and number of drivers and actuators (from six to three). The analyses presented in this paper are used to create the first design of the exoskeleton. Results of the cable-driven mechanism implementation confirm the feasibility of the proposed solution and open up new challenges in the hip cable-driven exoskeleton design.