This study examined the effectiveness of Flipped Inquiry-Based Learning (FIBL) in enhancing academic performance among Grade 12 Science students at Victoria High School during the 2025–2026 school year. Rooted in constructivist learning theory and the Community of Inquiry (CoI) model, FIBL integrates pre-class asynchronous activities with in-class inquiry-based tasks to foster active engagement, collaboration, and higher-order thinking. A quasi-experimental pretest-posttest control group design was used. Participants included 78 Grade 12 students randomly assigned to an experimental group (n = 39) receiving FIBL or a control group (n = 39) taught via traditional lecture methods. A validated teacher-made science test measured outcomes, with data analyzed using means, standard deviations, independent samples t-tests, and Cohen’s d. Pretest scores confirmed baseline equivalence between groups. Posttest results showed the FIBL group significantly outperformed the control group (M = 87.01 vs. M = 82.22; p < .001), with greater mean gains and a large effect size (Cohen’s d = 2.539). These findings affirm FIBL as a powerful strategy for boosting science achievement and promoting meaningful, student-centered learning.