P Kost is a business that provides temporary accommodation,established since August 2019 at Jl. Peninggaran Barat III No. 30, KebayoranLama Utara, South Jakarta. PKost rents out rooms or residential unitsequipped with basic facilities such as beds, fans/air conditioners, cupboards, private bathrooms, and motorbike parking access.bathroom, and motorbike parking access. According to the owner of PKost, currently thebooking process is still done manually, which requires tenants to come in person to book a room.directly to book a room. User Centreed Design (UCD) approachapproach is a design method that emphasises the importance of the user as thethe main focus in system development. UCD is known as an approachapproach to interactive system development, which aims to create systems that are useful from the designsystems that are useful throughout the design to implementation process, in order toto produce a product that meets the needs of the market. The study of user interface designinterface and user experience of the PKost Mobile Booking application with UCDshows that the final design provides a clear and structured guide for developers to implement the application.for developers in implementing the application. This designalso provides boarding house owners with a thorough understanding of the appearance andand functions of the application, so that they can provide feedback and make the necessary adjustments.necessary adjustments. Thus, this research successfully achievedthe goal of encouraging the development of an efficient application that meets theuser needs.