In the event of surgical management of metastases to the humeral shaft, intramedullary nailing (IMN) is often preferred to plate osteosynthesis (PO) fixation despite a lack of consensus. In this study, we hypothesized that plate osteosynthesis will be associated with better functional and pain outcomes, thus better quality of life. Eighteen patients with the diagnosis of humeral shaft metastatic fracture or impending fracture were extracted from a prospective database of 140 metastatic patients collected across three hospitals over a five-year period. Musculoskeletal Tumor Society (MSTS) score, Toronto Extremity Salvage Score (TESS), Quality of Life (QOL) and Brief Pain Inventory (BPI) score were gathered during the year following the surgery. Statistical analysis was performed to compare the mean score differences between the two surgical options at baseline and five follow-up visits. Both treatment options were associated with an increase in functional outcomes based on both MSTS and TESS, and a decrease in pain level. However, no significant difference was found in quality of life and between the two treatment modalities. Thus, based on our results, a similar improvement in functional status and pain level can be achieved surgically by either intramedullary nailing or plating osteosynthesis.