Teacher support is a crucial form of social support available to secondary school students, particularly within classroom settings. Numerous studies have investigated the relationship between perceived teacher support and academic achievement, consistently showing a positive predictive relationship. However, limited research has delved into the underlying mechanisms linking perceived teacher support and academic achievement, particularly within EFL (English as a Foreign Language) learning, especially in the Chinese educational setting. Therefore, this study aimed to examine the predictive influence of perceived teacher support on EFL achievement and the mediating role of behavioral engagement between these constructs. Data was collected from 688 Chinese secondary school students aged 12 to 15 (M =12.97, SD = 0.76). Results demonstrated a positive correlation between perceived teacher support, behavioral engagement, and EFL achievement. Furthermore, behavioral engagement fully mediated the relationship between perceived teacher support and EFL achievement. Implications, limitations, and directions for future research are also discussed.