Background <p><i>Abiotrophia defectiva</i> is primarily known for its association with endocarditis rather than intraocular infections. We reported a case of endophthalmitis caused by <i>Abiotrophia defectiva</i>, presenting as retinal vasculitis in its early stages, a phenomenon rarely documented in literature.</p> Case presentation <p>A 50-year-old Han Chinese man presented to the hospital with decreased vision in his left eye. Examination revealed mild vitritis, papilledema, retinal hemorrhages, and peripheral vascular sheathing in the left eye, raising suspicion of retinal vasculitis. In the following hours, his condition worsened dramatically, with the development of hypopyon and severe vitritis obscuring the visualization of the fundus, suggesting endophthalmitis. He subsequently underwent urgent anterior chamber irrigation, vitreous tap, and intravitreal injection. As the symptoms did not improve, a vitrectomy was performed. The culture results identified the presence of <i>Abiotrophia defectiva</i>. Following prompt and effective treatment, the patient’s visual acuity showed improvement.</p> Conclusion <p>This report delineates a rare case of endophthalmitis caused by <i>Abiotrophia defectiva</i> initially presenting as retinal vasculitis. It emphasizes the need for prompt recognition and treatment of atypical pathogens in postoperative ocular infections to enhance visual outcomes.</p>