The free fibula flap (FFF), based on the peroneal artery (PA) system, is the gold standard for mandibular reconstruction. Various anatomical variations in the infra-popliteal lower limb vascular system exist. These variations present as an intraoperative surprise to surgeons even after an unremarkable clinical vascular examination of the leg. Here, we report one such case, where we performed successful mandibular reconstruction after encountering a Type IIIA variation of infra-popliteal arterial vasculature.