Calciphylaxis is a rare but life-threatening disorder characterised by progressive vascular calcification, thrombosis, and painful skin necrosis, with high morbidity and mortality. Although most cases are reported in patients with end-stage kidney disease receiving dialysis, it can also occur in kidney transplant recipients, particularly in the setting of chronic allograft dysfunction and persistent disturbances in mineral metabolism. We report the case of a 70-year-old man who developed biopsy-confirmed calciphylaxis during chronic allograft failure secondary to chronic T-cell-mediated rejection and BK virus nephropathy following deceased-donor kidney transplantation. Additional risk factors included hyperphosphataemia, secondary hyperparathyroidism, long-term warfarin therapy for a mechanical aortic valve, and ongoing immunosuppression. Management involved multidisciplinary care, including cessation of warfarin with bridging intravenous unfractionated heparin, initiation of maintenance haemodialysis, optimisation of chronic kidney disease-mineral and bone disorder, intravenous sodium thiosulfate administered after each haemodialysis session, intensive wound care, pain management, and planned hyperbaric oxygen therapy. Despite these interventions, the patient developed varicella-zoster virus encephalitis and disseminated infection, resulting in progressive multisystem illness and death. This case highlights the multifactorial pathogenesis, diagnostic challenges, and poor prognosis of calciphylaxis in kidney transplant recipients with advanced allograft failure, particularly when anticoagulation cannot be safely discontinued because of a mechanical heart valve. Early recognition, histopathological confirmation, and prompt multidisciplinary management are essential; however, outcomes remain poor in patients with advanced graft dysfunction and ongoing immunosuppression.