This study aims to examine the effect of project-based learning on students' metacognitive skills at Bhakti Samudera Vocational High School, Surabaya. This study uses a quasi-experimental design with a control group and an experimental group to compare student outcomes with project-based learning and conventional learning methods. Data was collected through questionnaires before and after the intervention to measure students' metacognitive skills. The experimental group received project-based learning instructions, while the control group followed conventional methods. Data analysis involved calculating mean scores and paired sample t-tests to test statistical significance. The findings of this study indicate that students in the experimental group with project-based learning have higher metacognitive skills compared to the control group. This shows the positive impact of project-based learning on students' metacognitive development. The implications of this study highlight the importance of integrating project-based learning as a pedagogical approach in vocational high schools. By providing students with opportunities to apply knowledge in real-life situations, solve problems, and develop higher-order thinking skills, project-based learning enhances the metacognitive abilities needed in the modern world. However, it should be acknowledged that this study has limitations, such as the specific context of Bhakti Samudera Vocational High School and the use of a questionnaire as a measuring tool. Future studies should involve a more diverse sample and use more objective measurement methods to further explore the effects of project-based learning on metacognitive skills. In conclusion, this study shows that project-based learning has a positive and significant influence on increasing students' metacognitive skills at Bhakti Samudera Vocational High School. This supports the application of project-based learning as an effective teaching strategy to promote metacognitive development and equip students with the competencies needed for future success.