BACKGROUND Frontal sinus mucocele with intra-orbital extension represents a rare benign cyst-like lesion. Surgical management could be summarized in an open approach, an endoscopic marsupialization or a combined procedure. The present study reports a case of frontal mucocele with wide intra-orbital invasion treated with endoscopic marsupialization assisted by an image-guided navigation system. METHODS A 34-year-old African male was referred to the otolaryngology clinic for unilateral supraorbital swelling and post-nasal drip. A clinical ophthalmic assessment showed normal ocular movement, the absence of diplopia and normal visual acuity. CT scan showed a large soft tissue density lesion originating from the right frontal sinus with a supero-medial orbital erosion. The mass invaded the orbital cavity compressing and dislocating the eyeball forward and laterally. An image-guided ESS was performed according to Draft type IIa. Frontal mucocele's inferior wall was open in order to drain muco-purulent content. No complications were detected and the patient was completely recovered with open frontal sinus drainage at 4 months follow-up visit. CONCLUSIONS We have successfully treated a wide intra-orbital frontal mucocele with an endoscopic marsupialization thanks to image-guided navigation system support. This technology prevented an external approach with associated morbidity and longer hospitalization. CONCLUSIONS Navigated assisted endoscopic approach with marsupialization can be considered a safe treatment for FM with orbital extension. In particular, the image-guided system could be useful if bony landmarks are missing, if orbital erosion is present, and to completely drain lateral and multi-cystic lesions.