Klebsiella pneumoniae keratitis is uncommon but may progress rapidly in immunocompromised patients, leading to severe corneal destruction. We report a 42-year-old man with a history of lymphoma, hematopoietic stem cell transplantation, and chronic graft-versus-host disease who developed progressive keratitis after previous corneal ulcer repair. On presentation, visual acuity in the affected eye was hand motions, with a deep corneal ulcer, proliferative lesion, and peripheral neovascularization. Corneal culture grew K. pneumoniae. Despite intensive antimicrobial therapy, the patient required penetrating keratoplasty, anterior chamber reconstruction, and subsequent corneal repair procedures. The infection was ultimately controlled. This case highlights the increased risk of aggressive infectious keratitis in patients with post-transplant immune dysfunction and chronic ocular surface disease, and underscores the importance of early microbiological diagnosis, targeted antimicrobial therapy, and timely surgical intervention.