This study aims to provide an updated review comparing the complication rates and clinical outcomes of intramedullary nails and locking plates (LPs) in displaced proximal humerus fracture (PHF) management. We performed a systematic review of the Cochrane Central Register of Controlled Trials, Clinical Trials Registry, EMBASE, and PubMed. Studies with level III evidence or higher comparing intramedullary nails and LPs used for internal fixation of displaced PHFs were included. The Methodological Index for Nonrandomized Studies (MINORS) criteria and Cochrane Handbook for Systematic Reviews of Interventions 5.2.0 were used to assess the risk of bias. Our meta-analysis included a comparison of method-related complications, pain scores, range of motion (ROM), and functional scores. A total of 13 comparative studies were included: five randomized controlled trials, three prospective cohort studies, and five retrospective cohort studies. The total number of patients included was 1,253 (677 in the LP group and 576 in the intramedullary nail group). Superior Constant-Murley scores and external rotation ROM were found in the LP group during the early postoperative period. However, long-term functional scores and complication rates were comparable between the two groups. We conclude that intramedullary nailing and LP fixation are both equally effective for the treatment of displaced PHFs. Neither treatment appears superior at this time, and more large-scale randomized controlled trials should be conducted to further evaluate the potential benefit of LPs in the early postoperative period.