The present research broke new ground by investigating the influence of instructing English as a foreign language (EFL) learners in Vietnam to employ analytical rubrics for self-assessment on their writing proficiency. Sixteen students who were English majors were subjected to a 17-week training course on refining their writing abilities via the use of analytical rubrics. The study applied a comprehensive and rigorous experimental mixed-methods approach, consisting of two writing tests and semi-structured interviews. The research findings revealed that the practice of self-assessment utilizing analytical rubrics had a favourable influence on the writing performance of the students. This practice encouraged introspective thinking, reinforced self-regulation and self-monitoring, and improved language competence. The study suggests that EFL teachers in Vietnam and those in other contexts integrate the utilization of analytical rubrics for selfevaluation in their teaching procedures to upgrade their assessment techniques and pedagogical efficiency, which would eventually result in improved language learning outcomes for their students