This study investigates the use of Design Thinking in the creation of Augmented Reality (AR) and Virtual Reality (VR) applications for the preservation of Bali's Lontar Prasi cultural heritage. As a piece of Indonesian cultural patrimony, Lontar Prasi necessitates a novel approach to its preservation in the digital age. This research identifies UI/UX issues of AR/VR applications based on user problems through the phases of Emphasis, Definition, Ideation, Prototype, and Test. Changes were made to the icon display, 3D character information, and UI positioning as a result. With an average score of 80 (Excellent) on the System Usability Scale (SUS), testing revealed a substantial improvement in user satisfaction. These results demonstrate that the Design Thinking methodology is effective for addressing UI/UX issues and enhancing the app's acceptability. In conclusion, this approach can serve as a foundation for future advancements in the preservation of cultural heritage using modern technology for digitized cultural heritage