Introduction <p>Mobile health tools are evolving rapidly across healthcare sectors, particularly for enhancing patient self-care in trauma care. This research focuses on developing a self-care application specifically for chest trauma patients, aiming to improve their well-being. The study will also evaluate the application’s usability and effectiveness in supporting patient recovery.</p> Method <p>The study, conducted in 2024, involved three phases: identifying application specifications through literature review and expert interviews; developing the application using programming languages like Laravel Node.js, JavaScript, and MySQL; and evaluating usability and effectiveness with 21 chest trauma patients. The assessment utilized the USE questionnaire for usability and a researcher-developed questionnaire to measure effectiveness before and after application use.</p> Results <p>The educational elements for patients were divided into five categories: fractures, physical activities, respiratory activities, diet, medication use, and emergencies. Functional requirements included 25 items across eight categories, such as communication between doctor and patient, patient information recording, notifications, discussion forums, care teams, performance dashboards, news updates, and useful information. A web-based application was developed, achieving an 80.04% usability rating from patients. Data analysis revealed a significant improvement (<i>p</i> &lt; 0.05) in self-care behaviors—specifically in physical activity, diet, respiratory exercises, and medication adherence—after using the application.</p> Conclusion <p>Considering the results of this study, it can be said that the self-care application for chest trauma patients has performed well and has succeeded in gaining user satisfaction and proving effective. This health tool can be utilized to enhance the self-care performance of chest trauma patients at a national level.</p> Clinical trial number <p>Not applicable.</p>