This study investigates the implementation of the Blended-Collaborative Writing Instructional (BCWI) model to enhance English as a Foreign Language (EFL) student teachers' academic writing achievement. Academic writing is a critical skill for prospective educators, yet EFL learners often encounter challenges across the writing process, including idea generation, organization, revision, and editing. Employing a mixed-methods design, the study pursues three main objectives: (1) to examine whether the BCWI model improves student teachers' overall academic writing achievement, (2) to analyse whether the model enhances individual writing elements such as content, organization, vocabulary, language use, and mechanics, and (3) to explore student teachers' perceptions toward BCWI practices in academic writing classes. Findings reveal that the BCWI model significantly improves learners' ability to generate and structure ideas, refine drafts through iterative feedback, and develop autonomy in managing the writing process. Moreover, the model optimizes instruction, fosters collaboration, enriches materials, and incorporates constructive feedback through blended learning environments. Nevertheless, challenges emerged, including communication issues, unequal workload distribution, irresponsible group behaviour, and varying levels of digital literacy. These findings underscore the pedagogical potential of BCWI while highlighting the need for further research to refine its application across diverse learner profiles and proficiency levels.