Fibrous dysplasia (FD) is a benign progressive fibro-osseous lesion that is rarely associated with mucocele formation. This complication most probably results from the involvement and subsequent occlusion of the recesses of the sinuses by the dysplastic process. The frontoethmoid mucocele associated with FD represents a rare pathology, but it is important to consider this in the differential diagnosis of patients with proptosis, visual disturbance, and bony fronto-orbital swellings. Here, we describe the first case of frontoethmoid mucocele with underlying craniofacial FD, which was successfully treated by wide marsupialization via the transnasal endoscopic approach.