Background and Aim: Clot burden score (CBS) was designed to weight the thrombus status in cerebral anterior circulation. We performed a systematic review and metaanalysis to investigate the prognostic value of CBS in acute ischemic stroke (AIS) patients undergoing reperfusion therapies. Methods: We searched relevant databases for eligible articles reporting CBS in AIS patients. The effect sizes of good functional outcome, recanalization, or hemorrhagic transformation (HT) were pooled with random-/fixed-effect models. Sensitivity analyses and heterogeneity tests were performed. Results: Fifteen eligible studies enrolling 3302 AIS patients undergoing reperfusion therapies were included. AIS patients with per 1-point increase CBS were associated with good functional outcome (pooled odds ratio [OR]: 1.15, 95% confidence interval [CI]: 1.09-1.20) and high rate of recanalization (pooled OR: 1.27, 95% CI: 1.14-1.40). Results from categorical groups indicated high CBS at baseline was associated with higher likelihood of good functional outcome (pooled OR: 1.59, 95% CI: 1.30-1.94) and superior recanalization rates (pooled OR: 2.53, 95% CI: 1.79-3.57). Further stratified analyses showed in intravenous thrombolysis (IVT) alone group, increasing CBS was associated with good functional outcome (continuous pooled OR: 1.18, 95% CI: 1.10-1.27; categorical pooled OR: 3.38, 95% CI: 2.01-5.69) or recanalization (categorical pooled OR: 4.13, 95% CI: 2.00-8.51), but not in endovascular therapy alone group. No significant association was found between CBS and HT. Conclusions: CBS could be a predictor for AIS after reperfusion therapies in functional outcome and successful recanalization particularly in patients receiving IVT alone; while CBS might not be a predictor for HT.