The reduction of slipped vertebra is often performed during surgery for degenerative lumbar spondylolisthesis (DLS). This approach, while potentially improving clinical and radiological outcomes, also carries a risk of increased complications due to the reduction process. To address this, we introduced an innovative lever reduction technique for DLS treatment. This study aims to investigate the clinical efficacy, radiological outcomes, and complications of fusion with or without lever reduction.We conducted a retrospective review of prospectively collected data from a registry of patients who underwent lumbar fusion surgery for DLS, with a follow-up of at least 24 months. Self-reported measures included visual analog scale (VAS) for back or leg pain, Oswestry Disability Index (ODI), and the achievement of minimal clinically important difference (MCID). Radiological assessments encompassed spondylolisthesis percentage (SP), focal lordosis (FL), and lumbar lordosis (LL). Complications were categorized using the modified Clavien-Dindo classification (MCDC) scheme. Patients were assigned to the reduction group (RG) and non-reduction group (NRG) based on the application of the lever reduction technique. Clinical and radiological outcomes at baseline, immediately after surgery, and at the last follow-up were compared.A total of 281 patients were analyzed (123 NRG, 158 RG). Baseline patient demographics, comorbidities, and surgical characteristics were similarly distributed between groups except for operating time (NRG 129.25 min, RG 138.04 min, P = .009). Both groups exhibited significant clinical improvement after surgery (all, P = .000), with no substantial difference between groups (VAS, ODI, or the ability to reach MCID). Patients in RG showed statistically lower SP and higher FL during follow-up (all, P = .000). LL was comparable at different time points within each group or at the same time point between the two groups (all, P > .050). The overall complication rate (NRG 38.2%, RG 27.2%, P = .050) or specific complication rates per MCDC were similar between groups (all, P > .050). Patients in RG were predisposed to a lower risk of adjacent segment degeneration (ASDeg) (NRG 9.8%, RG 6.3%, P = .035).There were no significant differences in postoperative measures such as VAS scores for back and leg pain, ODI, the ability to reach MCID, overall complication rate, or specific complication rates per MCDC between surgical approaches. However, fusion with lever reduction demonstrated a notable advantage in restoring segmental spinal sagittal alignment and reducing the occurrence of ASDeg compared to in situ fusion.© 2023. The Author(s).