Objective: To describe a novel surgical technique for ventral orbital reconstruction after ventral orbitectomy by using a temporalis fascia transposition flap. Study design: Case report. Methods: A 7-year-old, spayed female Boston terrier was treated for multilobular osteochondrosarcoma arising from the cranial aspect of the left zygomatic arch, causing asymmetry of the face and mild exophthalmos of the left eye. A ventral orbitectomy with a wide surgical excision (including the cranial aspect of the zygomatic bone, the medial aspect of the lacrimal bone, and the dorsal aspect of the maxilla) was performed with preservation of the left eye. To support and maintain the left eye in a normal position, a temporalis fascia transposition flap was elevated and used. No complications occurred during the procedure. Results: Thirteen days after surgery, the referring veterinarian reported no complications. Complete excision was confirmed on histopathology. Eighty-three days after surgery, the dog remained asymptomatic with only mild epiphora of the left eye. Follow-up information from the owner 11 months after surgery indicated that the dog was asymptomatic with minimal ventral globe deviation. Conclusion: Additional ventral support of the globe after ventral orbitectomy via a temporalis fascia transposition flap resulted in an excellent functional and cosmetic outcome. Clinical significance: A temporalis fascia transposition flap can be used to reconstruct the ventral aspect of the orbit in dogs.