Purpose <p>This study aimed to assess the long-term outcomes of patients treated with plate osteosynthesis versus non-operative treatment for proximal humerus fractures (PHF) after a mean follow-up period of 10&#xa0;years.</p> Methods <p>A retrospective cohort study was conducted, including patients with PHF treated between 2004 and 2014. Patients were divided into two groups: those who underwent plate osteosynthesis (PO) and those managed non-surgically (NO). Functional outcomes, including range of motion, strength, and patient-reported quality of life were evaluated using standardized assessments such as the Constant-Murley score and Short-Form-36 (SF-36) questionnaire. </p> Results <p>A total of 241 patients (161 in the Surgical Group and 80 in the Non-Operative Group) were included in the study. With a mean follow-up of 10.4 ± 3.1&#xa0;years, both groups demonstrated comparable functional outcomes. The Constant-Murley score in the Surgical Group was 53.5 ± 21.8 compared to 60.1 ± 24.2 in the Non-Operative Group (<i>p</i> = 0.225). Complication rates were significantly higher in the PO group. The revision rate for patients treated with plate osteosynthesis was 37.9%. Patient-reported Quality of Life, assessed using the SF-12 questionnaire, revealed no significant differences between the Surgical and Non-Operative Groups.</p> Conclusion <p>This long-term follow-up study demonstrates that after a minimum of 5&#xa0;years, there were no significant differences in functional outcomes or quality of life between patients treated with plate osteosynthesis and those who were managed non-operatively for displaced proximal humerus fractures. Both treatment approaches can offer favorable results, and the choice of treatment should consider individual patient characteristics and preferences.</p>