A 50-year-old woman presented with acute onset of eye pain, redness, decreased vision, and photophobia. The patient had a history of cataract surgery performed 2 weeks prior. Clinical examination revealed significant conjunctival injection, corneal edema, and hypopyon. Anterior chamber tap and vitreous biopsy confirmed the diagnosis of endophthalmitis. Immediate intravitreal antibiotic therapy was administered, followed by a course of systemic antibiotics. Despite aggressive treatment, the patient experienced a significant loss of vision. This case underscores the importance of prompt recognition and treatment of endophthalmitis to prevent severe visual impairment.