A rare case of oromandibular Rhizopus oryzae infection is described in a 55-year-old woman with acute myeloid leukaemia and decompensated diabetes mellitus. The infection developed during induction chemotherapy when the patient was neutropenic. She was treated with a combination of amphotericin B lipid formulation and caspofungin plus surgery. Debridement surgery included excision of the lower lip, chin, floor of the mouth, a portion of the tongue, as well as mandibular resection at the level of the horizontal branches. Eight weeks of combined antifungal therapy were followed by secondary prophylaxis with amphotericin B lipid formulation during consolidation chemotherapy after achieving complete response of both leukaemia and mucormycosis. Reconstructive surgery was carried out including insertion of a new biomaterial porous mandibular prosthesis, which showed excellent functionality after long-term follow-up, followed by several plastic surgery procedures once good tolerability and no adverse effects of the prosthesis were observed. This case shows that a well-coordinated multidisciplinary approach is critical to increase the chances of clinical success in this life-threatening infection.