Human awareness of environmental control is getting bigger due to the increasingly urgent world situation. However, the lack of knowledge of sustainability behavior and consistent commitment results in not fully living a sustainable lifestyle. Furthermore, recent studies have shown that smart device is only a tool and does it not always support and build sustainable behavior; especially, if the system or tool does not interact much with the user. The aim of this study is that to design a mobile-based sustainable lifestyle gamification application which can motivate and build sustainable behavior. This study used a design thinking framework for practical and creative solutions by emphasizing a user-side approach. Finally, the user interface design with gamification features is considered to be able to improve a unique, fun and motivating user experience since it prioritizes user involvement by providing challenges and prizes as well as making users aware of the great impact of sustainable behavior. Therefore, from the two final designs, which are usability and performance tests, show that applications with light mode and dark mode designs have satisfactory scores; besides, they are recommended. However, the value in the light mode design concept is higher than the dark mode design.

Keywords : Sustainable Lifestyle, Gamification, Design Thinking, User Interface, User Experience.