This study examined the effects of project-based learning on EFL learners’ writing performance, critical thinking skills, and engagement in the writing classroom. A quasi-experimental time-series design involving a single group of participants was employed. The study was conducted with 18 EFL third-year undergraduate students enrolled in an Advanced Writing Skills course at Debre Markos University. It was selected through convenience sampling, while participant students were selected using a comprehensive sampling technique. The study employed writing tests, questionnaires, student-reflective journals, and interviews to collect data. The quantitative data were analyzed through one-way repeated measure MANOVA, paired samples t-test, and descriptive statistics, whereas the qualitative data were analyzed through narration. The findings drawn from the one-way repeated measure MANOVA showed the significant effects of project- based learning to enhance student's writing performance and critical thinking skills. Results from the questionnaire data, analyzed via a paired samples t-test, indicated higher student engagement levels while learning through project-based learning. In support of these findings, the qualitative data gathered through interviews and student-reflective journals also showed that project-based learning provided students with opportunities to engage in authentic writing tasks and enhanced the writing process. Ultimately, this study underscored the transformative potential of project- based learning in enhancing EFL students’ writing performance, critical thinking skills, and engagement—offering a meaningful shift toward more effective, student-centred language education.