This study examined the effects of Project-Based Learning (PjBL) on the scientific literacy and disaster preparedness of Grade 7 students in earthquake-related science instruction, and also determined whether a significant difference existed between pretest and posttest scores following the intervention. Grounded in Constructivist Theory and Experiential Learning Theory, the study employed a quasi-experimental one-group pretest–posttest design involving 36 Grade 7 students selected through purposive sampling. Two validated instruments were used: a 30-item Scientific Literacy Test and a 35-item Disaster Preparedness Questionnaire focused on earthquake concepts. Results revealed a significant increase in scientific literacy scores from pretest (M = 6.56, SD = 1.90) to posttest (M = 12.06, SD = 5.51), t(35) = 5.18, p < .001, with a large effect size (d = 0.863). Similarly, disaster preparedness scores significantly improved from pretest (M = 55.4, SD = 14.7) to posttest (M = 94.1, SD = 36.3), t(35) = 5.15, p < .001, also indicating a large effect size (d = 0.858). These findings indicate that PjBL significantly enhanced students’ scientific understanding and disaster preparedness skills. The study concludes that Project-Based Learning is an effective instructional approach for improving both scientific literacy and disaster preparedness in earthquake education. The findings provide empirical support for integrating PjBL within science education and Disaster Risk Reduction and Management (DRRM) initiatives. The proposed instructional materials may benefit science teachers, curriculum developers, and learners by promoting meaningful, contextualized, and experiential learning aligned with real-world disaster preparedness.