Optic atrophy has often been reported in children with biotinidase deficiency. The visual prognosis is usually poor. This report is of a 6-year-old boy with an early onset of biotinidase deficiency who presented with acute profound visual loss in both eyes. Fundoscopy revealed swollen discs in both eyes, and the imaging was consistent with bilateral optic neuritis. He was treated with systemic corticosteroid, and commenced on oral biotin. The final visual outcome was promising.