People are advised to receive a vaccine booster as the Delta and Omicron variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerge, but various adverse ocular reactions after vaccination have been reported. NAION following COVID-19 vaccination appears extremely rarely. Here, we report a case of a 61-year-old female with sudden painless blurred vision developing NAION after receiving ChAdOx1 nCoV-19 (AstraZeneca) vaccination and provide an in-depth explanation of the possible mechanisms regarding the hypercoagulable state after vaccination. Our report adds to the literature on potential adverse ocular effects after COVID-19 vaccination, and we as ophthalmologists recommend that clinicians should increase awareness of this possible ocular complication when evaluating patients with sudden visual disturbance with a recent history of vaccination.