BACKGROUND Postoperative rehabilitation exercise is a crucial stage for promoting joint function recovery and ensuring satisfactory outcomes. However, limited evidence exists to guide rehabilitation for younger total hip replacement (THR) patients. This study evaluates whether bed exercise after total hip replacement (THR) in patients under 65 improves hip function, quality of life, and reduces postoperative complications. MATERIAL AND METHODS A retrospective analysis of 389 THR patients was conducted, dividing them into Group A (bed exercise + gait re-education) and Group B (gait re-education only). Harris Hip Score and SF-36 were assessed at baseline and at 5, 17, and 35 weeks postoperatively. RESULTS Group A showed superior outcomes in hip function, quality of life, and fewer complications compared to Group B. At 5 weeks, Group A had a significantly higher Harris Hip Score (78.1±9.4 vs 71.5±12.9, P=0.036) and SF-36 scores (PCS: 82.6±14.1 vs 73.1±16.0, P=0.019; MCS: 80.5±16.9 vs 67.9±18.8, P<0.001). Postoperative complications, including deep vein thrombosis (2.7% vs 14.1%, P<0.001) and joint stiffness (1.1% vs 5.3%, P=0.020), were less frequent in Group A. CONCLUSIONS Bed exercise significantly enhances hip function, improves quality of life, and lowers complication rates, making it an effective postoperative rehabilitation approach for THR patients under age 65 years.