The current paper attempted to perform an action research to measure the effects of using project-based learning (PBL) on students’ writing performance and their perceptions towards the use of PBL in writing lessons. In response to research aims, objectives, and questions, the researcher adopted mixed methods with the use of quantitative and qualitative approaches. While pre-test and post-test were adopted to collect quantitative data to measure whether the use of PBL promoted students’ performance after action research interventions, student questionnaires and teacher interviews were respectively used to collect quantitative and qualitative data of students’ perceptions of using PBL to promote their writing performance. One hundred Grade 9 and four in-charge English students were selected as research samples. Overall, the analysis of research data reveals the following findings: 1) Descriptive statistics and results of sample t-test of test scores indicated that there was a statistically significant difference in writing test scores of students, implying that the use of project-based learning generated positive impacts on students’ improvement in writing proficiency; 2) Data collected from the questionnaire indicated that students expressed their positive perceptions towards the adoption of project-based learning to promote students’ writing competence owing to the enhancement of learning environment, improvement in learning motivation and the positive impacts of PBL on students’ writing skills; and 3) Data collected from teacher interview also support findings from the questionnaire concerning students’ perceptions of benefits of PBL, leading to their students’ positive perception towards the use of project-based learning. Based on the research findings, the implications for the use of PBL in writing teaching and learning in an effective manner are proposed.