This study investigates the efficacy of e-Geometry as a supplementary learning tool for Grade 10 students, focusing on its effect on mathematical competency and performance. The study wants to know the following: extent of the supplementary material in terms its content and features; the extent of the mathematical competency and performance. Also, it determines the significant relationship between the supplementary materials on mathematical competency and performance. This research uses a descriptive-qualitative method and selective sampling technique. The data from 122 students at Jacobo Z. Gonzales Memorial National High School, Biñan City, are collected through questionnaires via checklists and Five-Likert scales. Statistical analyses, including frequency counts, mean average, standard deviation, and Pearson correlation, are utilized to assess the relationship between the implementation of e-Geometry and students’ mathematical competency and performance. Results indicate that both the content and features of e-Geometry are rated as High, suggesting its positive potential as a supplementary learning material. The findings reveal that the content and features of the of the e-Geometry was considered as a highly-prepared material. Also, it determines the students' mathematical competency and performance, including comprehension, communication, and problem-solving skills, are approaching proficiency levels. The study also reveals a weak positive correlation between the effectiveness of e-Geometry and students’ mathematical competency and performance, the study emphasizes the material's favorable effect on learners' proficiency. The supplementary material had a significant effect on both the students’ mathematical competency and performance, thus the null hypotheses were rejected. The use of e-Geometry has a meaningful effect on mathematical skills. Despite the slight relationship, the supplementary material positively influenced learners' mathematical proficiency. Recommendations for improving supplementary material creation emphasize the need of a collaborative approach that includes instructors and students. Educators may acquire significant insights into their students' needs and preferences by actively engaging them in the design of learning materials, ensuring that the contents are adapted to their individual requirements. This participative method instills in learners a sense of ownership and participation, making the learning experience more meaningful and successful. Furthermore, educators should prioritize developing localized materials that are relevant to their students' cultural and educational contexts. Creating culturally relevant and contextually appropriate materials not only engages learners more successfully, but also meets the varying needs of students from various backgrounds, encouraging inclusion and equality in the classroom.