This study was conducted to address the ongoing decline in English proficiency among high school learners, specifically Grade 9 students in the District of Kalibo II. Grounded in Howard Gardner’s Theory of Multiple Intelligences, the study aimed to develop and evaluate the learning materials in English that are aligned with students’ diverse intelligences to improve learning outcomes and engagement. Utilizing the Research and Development (R&D) method, the study followed the 4D Model—Define, Design, Develop, and Disseminate—as a systematic framework in creating the instructional materials. The research was conducted at the Regional Science High School for Region VI in Kalibo, Aklan, with 123 Grade 9 students and five educators and content experts who served as validators. The instruments employed for data collection included the MI Survey and the Least Mastered Skills in English Test. These tools were used to determine students' intelligence strengths and identify the specific English competencies that required reinforcement. Findings revealed that integrating Multiple Intelligences in the design of English learning materials significantly enhanced the relevance, engagement, and effectiveness of the lessons. The expert validation further confirmed the appropriateness and pedagogical soundness of the developed materials. Based on the results, the study concludes that MI-based mastery learning materials can be a valuable tool for addressing the varied learning needs of students and improving English language proficiency. The study recommends the continued use and further enhancement of MI-tailored learning materials across other grade levels and subject areas.