Pleurostoma species are rare opportunistic fungal pathogens that primarily infects immunocompromised hosts, causing phaeohyphomycosis, manifesting as localised superficial or deep infections, pulmonary infections, central nervous system infections, or disseminated diseases. Fungi of the order Mucorales are known to cause rapidly progressive infections in the lungs, rhino-orbital-cerebral regions, and skin, with high mortality rates. We report the first case of rhino-orbital co-infection by these pathogens in a diabetic patient, resulting in irreversible vision loss. The patient presented with headache and facial swelling; imaging and endoscopy revealed sinus disease with purulent discharge. Following endoscopic sinus debridement, laboratory diagnosis was confirmed by integrating microscopic staining, fungal culture, and PCR. While early surgical intervention combined with amphotericin B therapy led to clinical improvement, the vision loss persisted. This case underscores the diagnostic challenges of rare fungal co-infections and emphasises the necessity of prompt combined surgical and antifungal intervention to improve outcomes.