Open inquiry is the fourth and highest level of an inquiry-based approach in science teaching and learning. Although previous research has highlighted several benefits of open inquiry, thus far, no studies have comprehensively reviewed its impacts using systematic and rigorous methodologies. Thus, the central aim of this review study was to develop a better understanding of the impacts of an open inquiry approach on students' learning in science. The search strategy was restricted to articles published in established scholarly databases (WOS, Scopus and ERIC), following the seven steps in conducting a systematic literature review process in educational research. As a result, 24 articles were extracted and qualified for inclusion in this review study. Finally, a thematic analysis was conducted to analyse the articles and five themes were generated: i) students' conceptual understanding, ii) students' motivation, iii) students' attitudes towards science, iv) students' scientific and thinking skills, and v) students' science literacy and other science-related skills. Although open inquiry positively impacted students' learning in science, the reviewed article also reported some challenges in its implementation, notably the need for classroom management, flexible teaching and learning, teacher-student interaction and teacher support. This review study provides a significant contribution to science education research, indicating that the highest level of an inquiry-based approach may not be the ‘best’ approach. However, this review offers a future opportunity for policymakers, teacher educators, science education academics, NGOs, science teachers, and other interested parties to promote inquiry pedagogy to improve students' learning in science.