INTRODUCTION AND IMPORTANCE: Spondylolysis is a pars interarticularis defect often associated with instability and pain. While commonly involving the inferior level, it can rarely present with disc degeneration or herniation at the superior level. Such coexistence poses unique biomechanical and clinical challenges, particularly in younger patients who require solutions that preserve spinal motion and minimize future degeneration. This report highlights a novel combined surgical approach while preserving spinal motion, addressing both pathologies. CASE PRESENTATION: A 27-year-old male presented with chronic low back pain and newly exacerbated radiculopathy. Imaging revealed bilateral L5 spondylolysis and a concomitant right-sided L4/L5 disc herniation compressing the L5 nerve root without significant spondylolisthesis. Conservative management was unsuccessful. A combined surgical approach using Buck's technique for the pars defect and discectomy at L4/L5 was performed. This strategy stabilized the spine, alleviated nerve compression, and preserved spinal motion. Postoperative imaging confirmed defect resolution and restored alignment without neurological deficits. At one-year follow-up, the patient reported marked pain relief and a return to normal activities. CLINICAL DISCUSSION: This rare coexistence required a tailored surgical strategy balancing motion preservation and structural stability. Buck's technique effectively stabilized the pars defect, while discectomy alleviated nerve root compression. This approach avoided fusion-related risks, ensuring long-term spinal functionality and reducing the likelihood of adjacent segment degeneration. CONCLUSION: The rare coexistence of L5 spondylolysis with L4/L5 disc herniation presents unique challenges. This case demonstrates that the first reported combination of Buck's technique and discectomy effectively resolves spinal instability and nerve compression while preserving motion.