BACKGROUND: Reconstruction of segmental bone loss due to malignancy, infection, or trauma is a challenge for the reconstructive surgeon. The combination of a vascularized fibular flap with a cortical allograft provides a reliable reconstructive option in the lower extremity. In this systematic review, we describe the outcome of this technique for the treatment of segmental bone loss. METHODS: A systematic review was performed on the use of a combined massive allograft and intramedullary vascularized fibula as a reconstruction method for large bone defects. We used PubMed, Embase, and the Wiley Cochrane Library. RESULTS: Seventeen clinical articles were included between 1997 and 2017, reporting 329 cases of lower-extremity reconstructions. A meta-analysis was performed on primary union rates. The main outcome measures were primary union rate, complication rate, reintervention rate, and function after reconstruction. All publications showed relatively high complication (5.9% to 85.7%) and reintervention rates (10% to 91.7%) with good primary union rates (66.7% to 100%) and functional outcome (range of mean Musculoskeletal Tumor Society [MSTS] scores, 24 to 29 points). CONCLUSIONS: The combination of a massive allograft with intramedullary vascularized fibula provides a single-step reconstruction method for large bone defects (>6 cm) in the lower extremity, with good long-term outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.