Unilateral arm paralysis is a common outcome of stroke and can have a devastating impact on its victims. In this study, we attempt to determine the impact of recruiting a post-stroke patient’s contralesional nervous system with the aim to reactivate the ipsilesional neural circuits and, ultimately, stimulate functional motor recovery. We establish such a phenomenon to be possible when a patient utilizes a non-paretic arm to support the movement/training of the paretic arm. In 10 subacute severe post-stroke patients, it was observed that a self-support exercise (SSE)—defined here as the self-guided biomechanical support provided by a non-paretic arm—unexpectedly triggered muscle activities in the supported paretic arm similar in intensity to the healthy activities of the non-paretic limb. Additionally, bilateral normalization of neural activation in the sensorimotor cortex between the stroke-affected and unaffected hemispheres during SSE was discovered during brain imaging. This strongly suggests the facilitation of interhemispheric communication in post-stroke motor recovery. We propose this finding may lead to a new era of available rehabilitation techniques.