BACKGROUND: Frosted branch angiitis (FBA) is a rare form of retinal vasculitis that can lead to significant vision loss. This case report presents a unique case of idiopathic FBA in a 2-year-old boy following pentavalent vaccination. CASE PRESENTATION: A previously healthy 2-year-old Emirati boy presented with sudden painless bilateral vision loss for one day. His mother noted difficulty walking and a lack of interest in visual stimuli. A few days prior, the child had received a pentavalent vaccination and experienced upper respiratory tract symptoms. Ophthalmic examination revealed bilateral dilated pupils, anterior chamber inflammation, and extensive retinal vascular sheathing. Investigations were unremarkable. The patient was treated with oral Prednisolone and Acyclovir. Within two weeks, the vision improved significantly, with complete resolution of retinal vasculitis observed within one month. Over the course of one year, the patient showed no recurrence of symptoms, and only small, stable retinal scars were noted. CONCLUSION: This case highlights the potential association between pentavalent vaccination and the onset of idiopathic FBA. The pathophysiology behind this association remains speculative, with potential mechanisms including immune dysregulation and molecular mimicry. Prompt recognition and treatment with systemic steroids can lead to favorable outcomes, emphasizing the importance of monitoring visual symptoms in pediatric patients following vaccination.