Recognized as an important teaching approach, blended teaching has been widely applied in English language instruction within university settings. Nonetheless, discrepancies exist in the reported results regarding the efficacy of blended teaching approach on university students' English learning outcomes. This study employs a comprehensive three-level meta-analysis method, analyzing 373 distinct effect sizes from 207 empirical studies. The three levels correspond to the sampling variance, the variance among effect sizes within individual studies, and the variance between different studies, allowing for a nuanced understanding of the factors influencing learning outcomes. Our findings reveal a significant overall positive impact of blended teaching on English learning outcomes. Specifically, we identify that the relationship between blended teaching and language achievement is nuanced, moderated by variables such as duration of implementation and interaction type, while remaining unaffected by teaching method, form of learning and blended mode. Additionally, we observe that the relationship between blended teaching and learners' personal characteristics is moderated by duration of implementation, teaching method and blended mode, yet remains independent of form of learning and interaction type. These findings are poised to inform and enhance English language pedagogy within the framework of blended teaching method.