Purpose: We present the first case of retinal vasculitis following intravitreal brolucizumab injection in South Korea. Case summary: A 76-year-old man with a medical history of hypertension who had been diagnosed with polypoidal choroidal vasculopathy of the left eye was treated with anti-vascular endothelial growth factor (VEGF) agents. Fifteen intravitreal ranibizumab, 17 aflibercept, and 12 bevacizumab injections were administered. On April 27, 2021, the anti-VEGF agent was switched to brolucizumab. Eight weeks after the first brolucizumab injection, the patient visited our clinic with conjunctival redness and cloudiness of vision in his left eye. A mild inflammatory reaction with grade 0.5 + cells was observed in both the anterior and vitreous chambers. Fundus photography showed cotton wool spots in the inferior and superior arcade, indicating acute retinal ischemia. Moderate leakage was observed at the optic disc along with cotton wool spots lesions and peripheral retinal capillaries on fluorescein angiography. Optical coherence tomography angiography (OCTA) showed significant reduction of vessel density (VD) in the superficial layers. The patient was treated with oral prednisolone (30 mg) and topical corticosteroids to relieve inflammation and vasculitis. After 1 week of treatment, the patient’s symptoms, inflammation, and cotton wool spots on the vascular arcades had regressed, and the VD of the superficial layers on OCTA had normalized. Conclusions: This is the first reported case of retinal vasculitis following intravitreal brolucizumab injection in South Korea. We suggest that VD of the superficial layers that is visible on OCTA can be a useful index to diagnose and track brolucizumab-induced retinal vasculitis.