Recent studies in mathematics education have focused on students' geometric problem-solving abilities, self-regulation, and the problem-based learning (PBL) model. The goal of this study is to examine how well junior high school students' self-regulation and geometric problem-solving skills are enhanced by the PBL model. In this study, quantitative methods using a quasi-experimental design were used. The sample consisted of 45 students from Amanatul Ummah junior high school in Mojokerto, Indonesia. Five types of instruments were utilized to collect data for this research, namely Syllabus, lesson plans, student worksheets, Self-Regulation Questionnaire (SRQ), and Geometry Problem-solving Test (GPST). The outcomes of the N-Gain test demonstrated how well the PBL model works to help students develop their capacity for self-regulation and geometric problem-solving. Apart from that, there are some notable differences between the traditional technique and the experimental class that is taught using the PBL paradigm. It is advised that similar trials be conducted in the future with a larger population and sample size. In both public and private junior high schools, it is strongly advised that more research be done with a larger population and sample size. Future researchers can also expand the study materials of geometry, not only to flat-sided geometric shapes but even further to curved-sided geometric shapes and also other subject matters.