AIM: To assess the association between Modic changes (MCs) and clinical outcomes in patients undergoing one-level lumbar fusion surgery. MATERIAL and METHODS: A retrospective cohort study included patients (>18 years) with single-level DDD treated with one-level lumbar fusion from 2016 to 2020 at a single center. Preoperative and 2-year postoperative outcomes were collected, including the Visual Analog Scales (VAS-back and VAS-leg), Oswestry-Disability-Index (ODI), Core-Outcome-Measures-Index (COMI-back) and Short-Form-Health-Survey-36 (SF-36). The association of patient reported outcomes measurements (PROMs) with preoperative MCs on MRI were assessed. Subjects with MC2 and MC3 were pooled in the No-MC1 group and compared to MC1 group. Continuous variables were compared using independent or paired t-tests, and non-parametric data with Mann–Whitney U or Wilcoxon signed-rank tests. Categorical variables were analyzed with Chi-square or Fisher’s exact test. RESULTS: Preoperatively, the MC1 group exhibited higher ODI scores (47.05±14.60 vs. 36.84±13.12; p=0.026) and lower SF-36-PCs (30.80±7.22 vs. 35.61±5.17; p=0.021) compared to the No-MC1 group. Postoperatively, no significant intergroup differences were observed. However, the MC1 group demonstrated greater improvements in ΔODI, ΔVAS-back, and ΔSF-36-PCs. Intragroup analysis revealed significant postoperative improvements in ODI, VAS-back, and VAS-leg in the MC1 group (e.g., ΔODI= 29.14±13.27; p= 0.007), while the No-MC1 group improved in ODI and SF-36-Mental Components (ΔODI= 21.10±12.26; p= 0.023; ΔSF-36-MCs= 5.98±12.44; p= 0.003). Notably, 7 patients did not reach the ΔODI minimum clinically important difference, with higher prevalence in the No-MC1 group (71.4%). CONCLUSION: One-level spinal fusion improves clinical outcomes in symptomatic degenerative disc disease. Patients with MC1 demonstrate greater functional and pain-related improvements compared to those with MC2 or MC3.