Barack Laundry is a laundry service business operating in Trini Sleman, a district in the Special Region of Yogyakarta. Laundry is an important household necessity, and many people are looking for trustworthy laundry service. Customer demand for laundry services continues to increase along with increasingly busy lifestyles. Although Barack Laundry's services continue to grow, there are still some problems faced by customers in the Trini Sleman area. One of the main problems is the lack of accessibility of information regarding service schedules, laundry status, and estimated costs. It is necessary to develop a mobile-based Barack Laundry application in Trini Sleman to overcome the problems that exist in Barack Laundry. The purpose of designing this mobile-based Barack Laundry application is to facilitate laundry management and customers so as to increase efficiency in the clothing ordering process. Apps can also extend the reach of laundry services to make them more accessible to customers. Features available on the app include a selection of clothing types and services with options such as washing, ironing, and both. The app also provides detailed booking information, scheduling of pick-up and drop-off times, and the option of online payment methods. The user-centered design method is used in this research by focusing on user needs. Kotlin programming language and MySQL database are also used in the process of developing this application. Based on the results of the research that has been done, it can be concluded that the mobile-based Barack Laundry application in Trini Sleman has successfully designed and implemented a mobile-based application for laundry ordering services in the region. This application has been carried out a black box testing process that has been carried out as many as 19 scenarios, with the final test results reaching 100%.