A rare case of palpebral cellulitis with simultaneous frontal sinusitis and osteomyelitis is reported. A healthy 45-year-old man presented with left upper eyelid swelling. He was given intravenous meropenem at the local hospital, but he failed to improve. Magnetic resonance imaging showed left frontal and maxillary sinusitis and upper palpebral cellulitis with an abscess. His temperature was 37.6°C, C-reactive protein was 1.36 mg/dL, thyroid hormone was elevated, left best-corrected visual activity was 1.2, and intraocular pressure was 25 mm Hg. He was then given cefazolin intravenously for 3 days but with no improvement. Therefore, the eyelid skin was incised. Postoperatively, the swelling improved significantly. Computed tomography demonstrated osteomyelitis of the left frontal sinus and osteolysis of the inferior wall. This case was considered a variation of Pott's puffy tumor. Bacterial cultures from the cellulitis abscess and sinusitis were negative. As for sinusitis, endoscopic sinusitis surgery (frontal sinus single sinus surgery [Draf III] and Kilian surgery) was performed. During 10 months of follow-up after the skin incision, no signs of recurrent eyelid swelling were observed.