The core of self-assessment (CSA) and critical thinking (CT) empower learners to observe and evaluate themselves. Although the literature on CSA and CT reflects a long history, little is known about their contributions to the learners' academic engagement (AE) and self-esteem (SE), particularly in the EFL context. Therefore, the present investigation intended to explore a structural model of English as a Foreign Language (EFL) university students' CSA, CT, and SE. Accordingly, the Core of Self-assessment Questionnaire (CSAQ), Watson-Glaser Critical Thinking Appraisal-form A (WGCTA), The SInAPSi Academic Engagement Scale (SAES), and The Foreign Language Learning Self-esteem Scale (FLLSES), were administered to 427 Iranian EFL university learners. The results of Structural Equation Modelling (SEM) indicated that EFL university students with high levels of CSA were more engaged and could build up high SE. Moreover, the effective role of CT in boosting AE and SE was also confirmed. The implications of this study may unveil new prospects for implementing learning-oriented assessment in the classroom and CT practices in language learning instruction and assessment.