Introduction: Lumbar canal stenosis is a common degenerative spinal condition characterized by narrowing of the spinal canal, leading to compression of the neural elements. It often results in symptoms such as low back pain, leg pain, and neurogenic claudication, which can significantly impair a patient’s quality of life. This study was designed to evaluate the functional and radiological outcomes of patients undergoing posterior lumbar interbody fusion with cage and decompression for lumbar canal stenosis. Methods & Matertials: This prospective study was conducted at the National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR), Dhaka, Bangladesh, from September 2021 to August 2022, involving 15 patients diagnosed with lumbar spinal stenosis. The collected data were compiled and analyzed using SPSS version 25.0. Result: The study demonstrated significant improvements following posterior lumbar interbody fusion with cage and decompression in patients with lumbar canal stenosis. Neurologically, all patients showed full recovery postoperatively as per Frankel grading. Radiologically, there was a marked reduction in slip angle (from 15.35° to 8.28°) and vertebral slip percentage (from 26.56% to 12.67%), along with restoration of lumbar lordosis (lumbar angle increased from 46.37° to 54.58°). Conclusion: It can be concluded that posterior lumbar interbody fusion (PLIF) with cage and decompression is an effective surgical approach for treating lumbar canal stenosis. The procedure led to significant neurological improvement, with all patients achieving full recovery postoperatively, as well as marked radiological enhancements, including reduced slip angle and vertebral slip percentage and improved lumbar lordosis.