The study examined the effectiveness of problem-based learning in enhancing the critical thinking skills of 222 Grade 12 Humanities and Social Sciences learners of Talipan National High School in Pagbilao, Quezon during the second semester, school year 2023- 2024. The first part of the study examined the effectiveness of problem-based learning in enhancing the critical thinking skills. The respondents had undergone problem-based learning and traditional learning modes in Inquiries, Investigations, and Immersion subject in the second semester. Pretest and posttest and the Critical Thinking Self-Assessment Scale Short Form were administered to the experimental and control group in the study. The second part presented the relational analysis of critical thinking skills and demographic profile of the respondents. The dimensions of interpretation, analysis, evaluation, inference, explanation, and self-regulation and the demographic profiles were described and correlated. The last part is determining the predictive variables of critical thinking skills. Teaching strategy and academic performance predict critical thinking skills. Recommendations to enhance critical thinking skills through the use of problem-based learning strategies were made in this study.