This quantitative study examined the mediating effect of student engagement on the relationship between attitude towards science and science achievement. A descriptive-correlational research design with mediation analysis was employed, involving 202 Grade 11 students from four private schools in the Diocese of Tagum, selected through simple random sampling. The study utilized two adopted questionnaires and one researcher-made questionnaire, with mean, Pearson r correlation, and Sobel z test as statistical tools. The results show that students exhibit a highly manifested attitude towards science and are actively engaged in science-related activities. Their science achievement is high, suggesting effective understanding and application of scientific concepts. A significant relationship was found between attitude towards science and both science achievement and student engagement. However, student engagement does not significantly correlate with science achievement and does not mediate the relationship between attitude and achievement. This indicates that while engagement may enhance interest and participation, it does not necessarily translate into improved science achievement. The findings suggest that other factors, such as instructional methods or cognitive abilities, may have a stronger influence on students' science achievement. These findings suggest that efforts should focus on directly strengthening students' attitudes toward science, as it plays a crucial role in their achievement. While engagement is strongly linked to attitude, it does not independently influence science achievement, indicating a need to explore how engagement can be effectively translated into better performance. Therefore, interventions should prioritize fostering a positive attitude while identifying ways to enhance the impact of engagement on science achievement.