This research aimed to examine the correlation between English teachers’ acceptance of Instant Response Systems (IRSs) and their perceived teaching effectiveness. Employing a mixed-methods approach, 151 EFL (English as a Foreign Language) teachers participated in the study. An online survey was employed to collect data regarding teachers’ acceptance of IRSs and their perceived effectiveness in teaching. Semi-structured interviews were conducted with 10 teachers to acquire nuanced insights into their perspectives on the effectiveness of integrating IRS tools into pedagogy. Findings revealed that predictors of teaching effectiveness included constructivist pedagogical beliefs, attitudes toward IRS implementation, perceived utility of IRSs, and facilitating conditions. The deployment of IRS-based tools demonstrated a positive impact on student motivation, engagement, and achievement. IRS-based tools were found to energize the class and provide information and feedback in a timely manner which enhanced the capacity of teachers to evaluate students’ learning progress.