An 81-year-old woman with diabetes mellitus presented with signs of orbital cellulitis and a gangrenous ulcer on the right palate. Biopsy analysis confirmed a diagnosis of necrotizing fasciitis. Surgical debridement of necrotic tissues and enucleation of the right eye were performed. Stenotrophomonas maltophilia was isolated from the specimens. The patient remained stable under antibiotic therapy and underwent reconstructive surgery. To the best of our knowledge, this represents a rare case of orbital necrotizing fasciitis developing secondary to S. maltophilia infection. Orbital necrotizing fasciitis is rare; the early clinical features may be similar to those of cellulitis. To prevent devastating complications, the former condition must be kept in mind, particularly in immunocompromised patients.