This quasi-experimental study investigated the impact of reflective thinking (RT) and self-evaluation (SE) interventions on improving academic mindfulness, subjective well-being, and second language performance, specifically speaking and writing proficiency, among Iranian intermediate EFL learners. The principal objective of this study was to examine whether these metacognitive interventions could improve learners’ mindfulness, emotional well-being, and productive language outcomes throughout the training period. Three groups of thirty intermediate EFL students were made up of the same number of students. A reflective thinking group utilizing Gibbs’ Reflective Cycle, a self-evaluation group employing TOEFL iBT-based checklists, and a control group undergoing traditional instruction. During this eight-week instructional period, participants completed all requisite pre- and post-assessments, evaluating alterations in academic mindfulness, subjective well-being, and productive language proficiency. Both RT and SE interventions demonstrated substantial enhancements across all assessed variables relative to the control group. The findings indicated that reflective thinking can more effectively enhance academic mindfulness, while self-evaluation results in greater improvements in subjective well-being and in both speaking and writing proficiency. The findings reveal that each of these approaches can differently affect learning, and such an impact is due to differences in metacognitive processes. Accordingly, such results emphasize the importance of designing instructional interventions that consider the specific developmental needs of EFL learners.