A primary challenge impeding optimal health outcomes in patients with disabilities is the lack of rehabilitation adherence. Immersive virtual reality emerges as a promising intervention with the potential to significantly enhance this key health outcome. This paper presents a situation-specific theory that outlines the mechanisms through which immersive virtual reality can promote rehabilitation adherence. Outcomes of immersive virtual reality encompass psychological (ie, motivation, self-efficacy, mood state) as well as physical responses (ie, pain management, muscle strength). Mechanisms by which immersive virtual reality influences outcomes are explained by proximal and distal mediators (attention, sense of presence, enjoyment). Possible moderators of these mechanisms (ie, age, gender, social support, trust in technology, cognitive status) are also described.