<![CDATA[The rapid advancement of science and technology in the 21st century requires science learning to focus on the development of higher-order thinking and essential 21st-century competencies. Students are expected not only to master scientific concepts but also to demonstrate critical thinking, creativity, problem-solving abilities, communication, collaboration, as well as scientific literacy and process skills. Project-Based Learning (PjBL) has been widely recognized as a relevant instructional model because it offers authentic, inquiry-oriented, and context-based learning experiences through project activities. This study aims to examine the contribution of PjBL to the development of 21st-century science competencies through a meta-synthesis approach. A Systematic Literature Review (SLR) was employed by analyzing and synthesizing findings from eight selected scholarly articles. The results of the meta-synthesis indicate that PjBL consistently enhances students’ conceptual understanding, scientific reasoning, and critical thinking through experimental activities, data analysis, and problem-solving processes. In addition, PjBL effectively strengthens 21st-century skills (4Cs), namely creativity, collaboration, communication, and critical thinking, which emerge through group work, project design, and scientific presentations. The structured stages of PjBL, aligned with scientific inquiry, also contribute to the improvement of students’ scientific literacy and science process skills. Although challenges remain in its implementation, such as time constraints and teachers’ readiness in project design, these limitations can be addressed through well-planned scaffolding, contextually relevant projects, and authentic assessment strategies. Overall, the findings confirm that Project-Based Learning is an effective and appropriate instructional approach for enhancing 21st-century science competencies. ABSTRAKPerkembangan sains dan teknologi abad ke-21 menuntut pembelajaran sains yang berorientasi pada penguatan kompetensi berpikir tingkat tinggi dan keterampilan abad 21. Peserta didik diharapkan tidak hanya menguasai konsep, tetapi juga memiliki kemampuan berpikir kritis, kreatif, pemecahan masalah, komunikasi, kolaborasi, serta literasi dan keterampilan proses ilmiah. Project-Based Learning (PjBL) dipandang sebagai model pembelajaran yang relevan karena memberikan pengalaman belajar autentik melalui kegiatan proyek yang kontekstual dan berbasis investigasi. Penelitian ini bertujuan menganalisis kontribusi PjBL terhadap pengembangan kompetensi sains abad 21 melalui pendekatan meta-sintesis. Metode yang digunakan adalah Systematic Literature Review (SLR) dengan mengkaji dan mensintesis delapan artikel ilmiah yang relevan. Hasil meta-sintesis menunjukkan bahwa PjBL secara konsisten meningkatkan penguasaan konsep sains, penalaran ilmiah, dan kemampuan berpikir kritis melalui aktivitas eksperimen, analisis data, dan pemecahan masalah. Selain itu, PjBL efektif memperkuat keterampilan abad 21 (4C), yaitu kreativitas, kolaborasi, komunikasi, dan berpikir kritis, yang berkembang melalui kerja kelompok, perancangan proyek, serta presentasi hasil. Tahapan PjBL yang selaras dengan proses ilmiah juga berkontribusi terhadap peningkatan literasi sains dan keterampilan proses ilmiah siswa. Meskipun implementasinya menghadapi kendala, seperti keterbatasan waktu dan kesiapan guru, hambatan tersebut dapat diatasi melalui perancangan proyek yang sederhana, relevan, dan didukung penilaian autentik. Secara keseluruhan, PjBL terbukti efektif dan layak direkomendasikan sebagai pendekatan strategis dalam pembelajaran sains abad 21.]]>
