This explanatory mixed methods study investigated the interrelationships among self-regulated learning (SRL) components, critical thinking and reading comprehension using PLS-SEM. For this purpose, a conceptual PLS-SEM model was evaluated on a sample of 183 Iranian elementary EFL learners. Then, 15 students were randomly selected to complete the follow up semi-structured interview. Three instruments including Motivated Strategies for Learning Questionnaire, the questionnaire of Critical Thinking ability in English Reading and a reading comprehension test were used to provide data sources for PLS-SEM models. The results of the quantitative analyses of measurement and structural models indicated that among the three components of SRL, cognitive strategies and metacognitive strategies significantly and directly affected critical thinking and reading comprehension. However, motivation had significant indirect effects on the outcome variables. Meanwhile, from among the SRL components, motivation had the strongest total effects on SRL. The qualitative findings of the study approved the predictive relationships of SRL components with reading comprehension and critical thinking. Moreover, the semi-structured interviews showed that the participants' effective use of self-regulated reading strategies, reading motivation and regulatory reading instruction were the major factors affecting EFL learners' SRL in reading comprehension and critical thinking.