PURPOSE: Exercise before surgery, as part of prehabilitation, aiming to enhance patients' functional and physiological capacity, has become widespread, necessitating an in-depth understanding. METHODS: A systematic search was conducted on Pubmed, Cochrane, and Scopus to examine the effect of exercise as prehabilitation, alone or in combination with other interventions, in patients with cancer. Interventional studies applying a single-arm, randomized controlled, or nonrandomized design were included. RESULTS: A total of 96 studies were included, and categorized according to cancer types, i.e., gynecological, breast, urological, gastrointestinal and lung cancer. For each cancer site, the effect of exercise, on physical fitness parameters and postoperative outcomes, including length of hospital stay and postoperative complications, was reported. CONCLUSION: Exercise as prehabilitation may have an important role in improving physical fitness, postoperative outcomes, and accelerating recovery, especially in certain types of malignancies.