A systematic review and network meta-analysis evaluated the effects of various preoperative rehabilitation programs on patients undergoing major abdominal surgery with high rates of postoperative complications, mortality, and health care utilization. Randomized controlled trials from the PubMed, Embase, Web of Science, Google Scholar, and Cochrane databases up to June 2025 were analyzed, focusing on maximal volume of oxygen uptake (VO2peak), 6-minute walk test (6MWT), length of stay (LOS), and postoperative complications. 31 studies with 2467 participants were included. High-intensity interval training (HIIT) was most effective for improving VO2peak (SUCRA 73.9%, MD 2.29, 95% CI: 0.52–4.06) and reducing postoperative complications (SUCRA 98.4%, OR 0.03, 95% CI). Aerobic exercise was best for increasing distance in the 6MWT (SUCRA 98.0%, MD 71.6, 95% CI: 17.44–125.90), achieving minimal clinical difference. Multimodal interventions were beneficial in reducing LOS (SUCRA 74.7%, MD -1.50, 95% CI: -3.02 to -0.02). Treatment strategies should be based on the patient's condition and determined based on real-time assessment and monitoring.