OBJECTIVES: Acute severe ulcerative colitis (ASUC) poses challenges to patient management owing to its high surgical rate. This study aimed to identify predictors of colectomy in patients with ASUC. DESIGN: This is a systematic review and meta-analysis. DATA SOURCES: PubMed and Web of Science were searched up to April 2024. ELIGIBILITY CRITERIA: Studies on the predictors of colectomy in adult patients with ASUC were eligible. DATA EXTRACTION AND SYNTHESIS: Two reviewers independently extracted the data using a prespecified data collection sheet. A qualitative synthesis was performed in tabular form. Random-effect meta-analyses were conducted using OR and 95% CI. RESULTS: Forty-two studies were included in the systematic review. The reported variables can be categorised into biomarkers, auxiliary examination findings, demographic and clinical characteristics, and drug factors. Through meta-analysis, albumin (OR 0.39 (95% CI 0.26 to 0.59) per 1 g/dL increment, I(2)=0.0%), high C reactive protein level (2.63 (1.53 to 4.52), I(2)=29.6%), high erythrocyte sedimentation rate level (2.92 (1.39 to 6.14), I(2)=0.0%), low haemoglobin level (2.08 (1.07 to 4.07), I(2)=56.4%), fulfilling the Oxford criteria (4.42 (2.85 to 6.84), I(2)=0.0%), extensive colitis (1.85 (1.24 to 2.78), I(2)=47.5%), previous steroids (1.75 (1.23 to 2.50), I(2)=17.7%) or azathioprine (2.25 (1.28 to 3.96), I(2)=0.0%) use, and sarcopenia (1.90 (1.04 to 3.45), I(2)=0.0%) were identified as valuable predictors for colectomy within 1 year. The ulcerative colitis endoscopic index of severity (OR 2.41 (95% CI 1.72 to 3.39), I(2)=1.5%) was the only predictor found to predict colectomy over 1 year. CONCLUSION: Identification of these predictors may facilitate risk stratification of patients with ASUC, drive personalised treatment and reduce the need for colectomy.