<b><i>Introduction:</i></b> Predictive biomarkers for the therapeutic outcome of induction therapy with systemic corticosteroid for active ulcerative colitis (UC) have not been established. This study aimed to investigate whether neutrophil-to-lymphocyte ratio (NLR) and/or platelet-to-lymphocyte ratio (PLR) can be predictive biomarkers for the therapeutic outcomes of systemic corticosteroid therapy in UC. <b><i>Methods:</i></b> This was a single-center retrospective cohort study. In total, 48 patients with UC who received induction therapy with systemic corticosteroid were enrolled. Based on the achievement of clinical remission after 8 weeks of treatment, the patients were divided into the remission group (<i>n</i> = 28) and the nonremission group (<i>n</i> = 20). Clinical characteristics, NLR, and PLR at baseline between the remission and nonremission groups were compared via a univariate analysis. The independent risk factors of nonremission were identified via a multivariate analysis. <b><i>Results:</i></b> The baseline Mayo score, platelet count, lymphocyte count, C-reactive protein (CRP) levels, NLR, and PLR between the 2 groups significantly differed. The nonremission group had higher NLR and PLR than the remission group (4.70 [3.04–11.3] vs. 3.10 [1.36–16.42]; <i>p</i> &#x3c; 0.05, and 353.6 [220.3–499.8] vs. 207.2 [174.4–243.6]; <i>p</i> &#x3c; 0.001, respectively). A multivariate analysis revealed that a Mayo score of ≥9, CRP level of ≥1.26 mg/dL, and PLR of ≥262 (hazard ratio: 23.1, 95% confidence interval: 1.29–413.7, <i>p</i> = 0.033) were considered independent risk factors for nonremission. <b><i>Conclusion:</i></b> This report first identified the efficacy of NLR and PLR as candidate biomarkers for predicting the therapeutic outcomes of systemic corticosteroid therapy in UC.