<![CDATA[The management of activities within the Islamic Spiritual Student Unit (UKKI) requires an information system that supports effective information delivery and activity management. This study aims to evaluate and improve the UI/UX design of a mobile application for managing UKKI activities using the Design Thinking method. The research process consists of five stages: empathize, define, ideate, prototype, and test. The evaluation involved two rounds of usability testing with eight participants: three UKKI members, four administrators, and one supervisor. Task completion effectiveness and the System Usability Scale (SUS) were used to evaluate usability, while Heuristic Evaluation was conducted to identify interface issues based on usability heuristics. The first testing stage achieved task completion effectiveness rates of 91.67% for members, 93.06% for administrators, and 90.00% for supervisors. Following evaluation and design revisions, the second stage achieved effectiveness rates of 95.83% for members, 95.83% for administrators, and 100.00% for supervisors. System Usability Scale (SUS) scores changed from 82.50 to 90.80 for members, from 86.87 to 95.00 for administrators, and from 75.00 to 80.00 for supervisors. These results descriptively indicate changes in task completion effectiveness and perceived usability following design iteration. This study provides a UI/UX design for the UKKI mobile application that has been evaluated through usability testing and Heuristic Evaluation]]>
