Fungal sinusitis occurs as airborne fungi adhere to the mucous membranes of the nasal cavity and sinuses through respiratory inhalation. Fungal sinusitis manifests in various forms from simple irritation of nasal sinus mucosa to life-threatening diseases. Fungal sinusitis may be asymptomatic, the symptoms of fungal sinusitis include purulent rhinorrhea, facial pain and postnasal drip. Diagnosis of fungal sinusitis through nasal endoscopy is notably difficult. In computed tomography, fungal sinusitis is characterized by observations such as calcifications, heterogenous soft tissue density lesions, and periosteal thickening. The treatment is the endoscopic removal of fungal ball completely widening the sinus ostium. The sphenoid sinus, being the closest paranasal structure to the skull base, requires attention due to its adjacency to vital structures like the internal carotid artery and optic nerve. Preoperative imaging scrutiny and a meticulous surgical strategy should precede the treatment involving the sphenoid sinus. The author represents a successful case of the sphenoid fungal sinusitis patient of high-risk systemic disease with old age under local anesthesia.