Proximal humerus fractures (PHF) are common in the elderly, accounting for significant morbidity and mortality. Non-surgical treatment is a common option for low-demand elderly patients, but it can lead to unsatisfactory functional outcomes in some cases.The identification of predictive factors for poor prognosis in non-surgical management remains unclear. This study aimed to determine the predictive factors for poor prognosis in elderly patients treated non-surgically for displaced PHF and to assess associated complications. A retrospective cohort study was conducted involving patients aged 60 years or older with displaced PHF treated non-surgically from May 2020 to January 2023 at a reference hospital for orthopedic trauma. The primary outcome was functional assessment using the American Shoulder and Elbow Surgeons (ASES) scale at 12 months. Predictive factors such as metaphyseal fracture comminution, Pain Catastrophizing Scale (PCS) scores, and radiographic criteria were analyzed. Multivariate regression analyses were performed to identify independent predictors of poor outcomes. Out of 140 initially selected patients, 103 met the inclusion criteria and completed the follow-up. The mean ASES score was 71.3±25.4 points. Multivariate analysis identified metaphyseal comminution (p < 0.001) and PCS scores ≥ 30 (p < 0.001) as significant predictors of poorer functional outcomes. Complications were observed in 17.4% of patients, including osteonecrosis (6.7%), nonunion (4.9%), and persistent pain and stiffness (5.8%). Metaphyseal comminution and high PCS scores are significant predictors of poor prognosis in elderly patients undergoing non-surgical treatment for displaced PHF. These findings highlight the importance of considering both biomechanical and psychological factors when managing proximal humerus fractures in this population. Further studies with larger sample sizes and prospective designs are needed to validate these findings and refine treatment strategies.