During walking, arm swing helps maintain postural balance and stability, but it does not aid in body propulsion. Human bipedal locomotion makes the upper limbs passively swing without engaging much upper limb muscle force or effort. The central idea of this thesis is to capture the kinetic energy of the arm swing during walking and transfer it to the lower limbs via a wearable exosuit to reduce the lower limb muscle efforts during walking. The Arm-Leg Interactive Coupling Exosuit (ALICE) is designed with cable-pulley system to harness shoulder and elbow movements to support the hips and ankles during walking. ALICE employs two coupling methods, shoulder-hip coupling and elbow-ankle coupling. The shoulder is coupled with the hip contralaterally, while the elbow is coupled with the ankle ipsilaterally to match the natural walking pattern. Therefore, shoulder flexion results in hip flexion, and elbow flexion initiates plantarflexion of the ankle during toe-off. The proposed concept was validated through human subject experiments involving 15 healthy young adults who walked on a treadmill for 5 minutes with and without the device. Walking kinematics, muscle activity, foot pressure, and metabolic cost were recorded to compare differences in walking biomechanics and energetics between three conditions - BL, S1 (device worn but disengaged) and S2 (device worn and engaged). A repeated measures analysis of variance (ANOVA) followed by post hoc analysis was used to identify the effects of shoulder-hip coupling, elbow-ankle coupling, and their combined effects. The results indicate that the proposed concepts indeed generate the expected outcomes of reducing lower limb muscle activity in exchange for the increased effort of upper limb muscles.