This qualitative review aims to describe the current status of problem-based learning (PBL) implementation in mathematics and identify research gaps in the area of investigation. Literature was searched using the ERIC and Google Scholar search engines. The inclusion/exclusion criteria included: articles published in reputable journals in English since 2015; use PBL as an instructional strategy; include critical thinking, problem-solving, and creative thinking skills or explore the PBL process; as well as studies conducted at the secondary school level; those using well-defined research design, process, and procedures; use reliable and valid data collection instruments; rigors maintained; clear discussion and precise conclusion. Based on these criteria, 14 primary studies were selected and reviewed. The results show that PBL improves mathematical critical thinking, problem-solving, and creative thinking skills. Second, teachers' and students' adaptation to the PBL environment encompasses multiple stages of conceptualization and reconceptualization of its basic features. In addressing the challenges associated with the complex nature of PBL implementation during the shift from the conventional direct instruction model to the PBL environment in secondary school mathematics instruction, these studies fall short of producing concrete results and knowledge.