<![CDATA[The selection of extracurricular activities at SMKN 4 Payakumbuh has previously relied on subjective considerations, making it difficult for students to determine activities that match their interests, abilities, and characteristics. This study aims to develop a web-based Decision Support System (DSS) for extracurricular selection using the Fuzzy Mamdani method. This research employed the Research and Development (R&D) method with the Incremental Software Development Life Cycle (SDLC) model, consisting of requirements analysis, system design, implementation, integration, and testing. The system was developed using PHP and MySQL. The Fuzzy Mamdani method was applied through fuzzification, MIN-MAX inference, and Centroid defuzzification to generate extracurricular recommendations based on three criteria: academic achievement, interest, and personality. System testing included Functional Suitability, Usability, Compatibility, and instrument validity. The results showed that Functional Suitability and Compatibility each achieved 100%, while Usability achieved 84.44%. The instrument validity test obtained an average Aiken’s V value of 0.93. These results indicate that the developed system meets the required functional, usability, and compatibility aspects and can assist schools in providing more objective, systematic, and efficient extracurricular recommendations according to students’ characteristics.]]>
