Background: It is well known that soluble suppression of tumorigenicity 2 (sST2) predicts heart failure outcomes. Little attention has been paid to its use in atrial fibrillation (AF). We investigated whether sST2 is involved in AF formation and recurrence after catheter ablation. Methods: A systematic review and meta-analysis study was completed. Until the end of November 2023, the potential articles from Cochrane, OpenMD, PubMed, and ScienceDirect were collected. The assessment of study quality was conducted using the Newcastle-Ottawa scale (NOS). All relevant data from eligible studies were extracted. A random effect model was used for the pooled analysis. Results: A total of 14582 participants from 19 studies were involved in this study. The sST2 level was greater in individuals with AF than those with sinus rhythm (standardised mean difference [SMD] = 0.45; 95% confidence interval [CI] = 0.29 to 0.61; p < 0.01). Elevated sST2 levels were correlated with an increased likelihood of developing AF (hazard ratio [HR] = 1.07; 95% CI = 1.00 to 1.14; p = 0.04). A higher sST2 level was found in individuals with recurrent AF (SMD = 0.78; 95% CI = 0.32 to 1.23; p < 0.01). An elevated level of sST2 was related to a greater recurrent AF risk (HR = 1.17; 95% CI = 1.04 to 1.32; p = 0.01). Conclusions: The circulating biomarker sST2 has an essential role in AF development. Moreover, sT2 is a significant predictor for recurrent AF after a successful catheter ablation procedure. © 2025 Belgian Society of Cardiology.