Lumbar spinal stenosis (LSS) is a common degenerative condition in older adults, leading to chronic low back pain, neurogenic claudication, reduced functional capacity, and impaired quality of life. It most frequently affects the L4/L5 and L5/S1 levels. Surgical intervention improves patient outcomes when conservative treatment fails. Coexisting conditions, such as prostate cancer with spinal metastases, increase the risk of fractures and bleeding. Refusal of blood transfusions by Jehovah’s Witnesses requires comprehensive patient blood management (PBM), including preoperative optimization, meticulous intraoperative hemostasis, and postoperative support. A 72-year-old man with chronic low back pain, neurogenic claudication, and progressive neurological deficits, with a history of prostate cancer and complete refusal of blood transfusions, presented for treatment. Magnetic resonance imaging (MRI) revealed critical stenosis at L4/L5 and degenerative changes at L2–L4. Conservative therapy was ineffective. The patient underwent transforaminal lumbar interbody fusion (TLIF) with pedicle screw fixation and a biopsy of L3. Recovery was uneventful, neurological deficits resolved, and follow-up MRI confirmed adequate decompression of neural structures. Histopathology demonstrated prostate cancer metastases. The procedure provided decompression and spinal stabilization while minimizing blood loss through PBM measures, including optimization of erythropoiesis, tranexamic acid administration, precise hemostasis, and monitoring of hidden blood loss. TLIF with PBM is safe and effective in older patients with severe lumbar stenosis, coexisting malignancy, and transfusion restrictions. Multidisciplinary planning and meticulous surgical technique support neurological recovery and allow continuation of oncological treatment.