Cancer prehabilitation, a process on the continuum of care that occurs between the time of cancer diagnosis and the beginning of acute treatment, includes physical and psychological assessments that establish a baseline functional level, identifies impairments, and provides targeted interventions that improve a patient’s health to reduce the incidence and the severity of current and future impairments. There is a growing body of scientific evidence that supports preparing newly diagnosed cancer patients for and optimizing their health before starting acute treatments. This is the first review of cancer prehabilitation, and the purpose was to describe early studies in the noncancer population and then the historical focus in cancer patients on aerobic conditioning and building strength and stamina through an appropriate exercise regimen. More recent research shows that opportunities exist to use other unimodal or multimodal prehabilitation interventions to decrease morbidity, improve physical and psychological health outcomes, increase the number of potential treatment options, decrease hospital readmissions, and reduce both direct and indirect healthcare costs attributed to cancer. Future research may demonstrate increased compliance with acute cancer treatment protocols and, therefore, improved survival outcomes. New studies suggest that a multimodal approach that incorporates both physical and psychological prehabilitation interventions may be more effective than a unimodal approach that addresses just one or the other. In an impairment-driven cancer rehabilitation model, identifying current and anticipating future impairments are the critical first steps in improving healthcare outcomes and decreasing costs. More research is urgently needed to evaluate the most effective prehabilitation interventions, and combinations thereof, for survivors of all types of cancer.