Endogenous endophthalmitis is an ocular emergency, with severe sight-threatening complications. We report a case of unilateral endogenous Klebsiella pneumonia endophthalmitis with a large sub-retinal abscess in a 39-year-old lady that developed four days after presentation with sepsis secondary to urinary tract infections and pyelonephritis. Despite immediate treatment with intravenous (IV) and intravitreal antibiotics, her eye condition deteriorated. A pars plana vitrectomy was performed, and the sub-retinal abscess was removed, followed by silicone oil tamponade. Subsequently, she regained her vision to 6/36 with complete regression of the intraocular inflammation and sub-retinal abscess.