This study aimed to determine the students’ perceptions of Problem-Based Learning (PBL) and its effectiveness in enhancing scientific understanding, critical thinking, and engagement in Science 10. Specifically, it sought to describe the respondents’ profile in terms of age and gender, assess their perceptions of PBL in terms of activities, instructional methods, assessment tools, and overall effectiveness, identify the problems encountered in the implementation of PBL, and propose appropriate interventions to address these challenges. The study employed a descriptive research design and involved forty-two (42) Grade 10 students of Calintaan National High School, Calintaan, Occidental Mindoro. Data were collected using a structured questionnaire and analyzed using frequency counts, percentages, and weighted mean. The findings revealed that most respondents were aged 15 to 16 years old, with a slightly higher proportion of male students. Students perceived that PBL activities such as group work, brainstorming, and sharing of ideas were frequently implemented. Instructional methods and assessment tools related to PBL were also generally rated as “often” utilized. Overall, students demonstrated a positive perception of the effectiveness of PBL in enhancing their scientific understanding, critical thinking, and engagement. However, several challenges were identified, including issues related to teacher motivation, time constraints, and difficulties in implementing PBL strategies. Despite these concerns, the overall level of problems encountered was considered only slightly serious. Respondents strongly supported interventions such as teacher training, increased motivation, provision of instructional materials, and regular supervision to improve PBL implementation. The study concludes that Problem-Based Learning is an effective instructional approach in Science 10, as perceived by students. It is recommended that educators continue to implement and strengthen PBL strategies with institutional support. Future research may explore its application in other contexts and the integration of technology to further enhance learning outcomes.