The aimed of this study is to determine the effectiveness of inquiry-based learning on students’ level of engagement and critical thinking skills. The study used pre-experimental single group pretest-posttest design to grade 10 students from selected schools in the Division of Lipa City. Findings revealed that the level of behavioral engagement among student after the utilization of IBL was highly engaged. Likewise cognitive and emotional engagement among student was evident. Furthermore, students’ level of critical thinking skills after the implementation of IBL were approaching proficiency. Lastly, significant differences were seen on students’ level of engagement and critical thinking skills was seen after the implementation of IBL.