Purpose <p>Histological remission has emerged as a promising target that may improve long-term outcomes in patients with ulcerative colitis (UC). The aim of this study was to investigate correlations between clinical, endoscopic, and histological remissions and the predictive value of histological remission on long-term outcomes in patients with UC receiving conventional therapy.</p> Methods <p>A retrospective study was conducted involving 183 patients with UC who underwent histological assessment between August 2004 and May 2018. Concordance among clinical, endoscopic, and histological remissions was evaluated using Fleiss kappa statistics. Cox multivariate regression analysis was performed to identify independent factors associated with long-term outcomes, including corticosteroid use, biologics requirements, hospitalization, and composite outcome of disease progression.</p> Results <p>At baseline, 84.7% of patients were treated with 5-aminosalicylic acid and 15.3% with immunosuppressants. Histological remission exhibited fair agreement with endoscopic remission (κ = 0.280, 95%CI = 0.276–0.285, <i>P</i> &lt; 0.001). Cox multivariate analysis revealed histological remission served as an independent protective factor against the need for corticosteroid (HR: 0.242, 95%CI = 0.087–0.675, <i>P</i> = 0.007), biologics requirements (HR 0.323, 95%CI = 0.114–0.914, <i>P</i> = 0.033), hospitalization for acute severe UC (HR 0.270, 95%CI = 0.083–0.875, <i>P</i> = 0.029), and disease progression (HR 0.340, 95%CI = 0.164–0.708, <i>P</i> = 0.004) over a median 5-year follow-up period.</p> Conclusion <p>Histological remission showed fair agreement with endoscopic remission and independently predicted better clinical outcomes, including reduced corticosteroid use, decreased biologics requirement, and lower rates of hospitalization and disease progression in patients with UC receiving conventional therapy.</p>