Myelin oligodendrocyte glycoprotein (MOG)‐associated disease is an autoimmune disease of the central nervous system, associated with the presence of immunoglobulin G serum antibodies against MOG. Recent data have allowed characterization of the clinical spectrum of MOG‐associated disease, which is now considered a new disease entity, distinct from multiple sclerosis and neuromyelitis optica spectrum disorders. Optic neuritis is the most common clinical presentation of MOG‐associated disease in adults, both at disease onset and during the disease course, and has several distinct clinical and paraclinical features. Immunoglobulin G serum antibodies against MOG‐positive optic neuritis is often bilateral and associated with optic disc swelling and a longitudinally extensive abnormal magnetic resonance imaging signal involving the retrobulbar portion of the optic nerve. The visual acuity during the acute attack is severely decreased, and the response to corticosteroids is often rapid and prominent. However, early relapses after steroid cessation are common, and a subset of patients is left with a permanent visual disability. In this review, we discuss the clinical and paraclinical features of immunoglobulin G serum antibodies against MOG‐positive optic neuritis in adults, and focus on the distinctive features that can enable its early diagnosis. Therapeutical considerations at the acute stage and for relapse prevention are further deliberated.