Background: Implementing English medium instruction (EMI) has become a proliferating measure in higher education to embrace globalization. Nevertheless, university students reported various challenges in taking EMI courses. Objectives: This study investigated the effect of the computer-mediated terminology pretraining on university students' EMI success, regarding their efficacy in taking EMI courses, self-directed learning (SDL), and EMI performance. Methods: Participants were 86 university students enrolled in two EMI educational psychology courses. Students in the experimental group were assigned computer-mediated terminology pretraining tasks for 13 consecutive weeks, while those in the control group did not receive the pretraining assignment. Both groups were taught using the problem-based learning (PBL) pedagogy with a computer-mediated structured whiteboard. Results and Conclusion: The study findings showed that the computer-mediated terminology pretraining enhanced learners' response efficacy. Both groups increased their SDL under the PBL pedagogy. Besides, multigroup comparison results demonstrated that efficacy in EMI positively predicted SDL, which was related to better EMI performance in the experimental group but not in the control group. Notably, students conducting computer-mediated terminology pretraining remitted the influence of English ability on their EMI performance. Major Takeaways from the Study: Implications for instruction were made to use the combined strategy of the computer-mediated terminology pretraining and PBL in EMI courses to facilitate university students' efficacy in taking EMI courses, self-directed learning behaviours, and EMI performance.