This study aims to develop and evaluate contextualized supplementary learning materials to enhance Grade 7 students' problem-solving skills in mathematics, specifically addressing difficulties in understanding percentage increase and decrease. Using a design-based research approach informed by the 4D Model, Define, Design, Develop, and Disseminate, the research involved identifying learners’ least mastered competencies through diagnostic tests, developing locally relevant teaching materials integrated with community-based resources, and evaluating the outcomes. Descriptive statistics were used to analyze both learner and expert feedback, which indicated high acceptability and significant improvements in students' problem-solving skills. By effectively applying mathematical concepts to real-life situations, the materials enhanced students' interest and understanding. Future research could explore the use of contextualized materials in more diverse school settings to validate their effectiveness across different contexts. Overall, the findings suggest that culturally relevant and community-based instructional resources can effectively address learning gaps, improve student performance, and promote meaningful mathematical understanding. This study underscores the importance of contextualized instructional materials in enhancing student achievement and engagement in mathematics education.