Orbital cellulitis is a potentially sight and life-threatening complication of acute sinusitis, and the association with osteomyelitis is rare in the era of antibiotic-use. A 13-year-old girl presented with coryzal symptoms and severe headache, with a CT head being consistent with a diagnosis of pansinusitis and orbital cellulitis with abscess formation. She proceeded to have surgical drainage through a combined endoscopic and external approach to intraorbital abscess drainage with frontal trephine. She was also diagnosed with progressive calvarial osteomyelitis involving the right frontal bone, treated with a prolonged course of intravenous antibiotics. Our case highlights the importance of a high index of suspicion for complications of sinusitis. Multimodal imaging is essential to establish the extent of infection, and a multi-disciplinary approach is integral to manage this rare complication.