Emergency care is very complex in that it requires patient-centered care in a coordinated manner among multiple providers in a highly distractible, unpredictable and stressful environment. Sharing information efficiently between providers in this context is difficult. Connecting emergency providers with each other through a digital communication channel could improve the efficiency of information sharing and emergency care. This study describes the development process of PIMPmyHospital, a mobile app dedicated to emergency department physicians and nurses to collaboratively manage their patients. We relied on a user-centered design process involving caregivers from a pediatric emergency department. The process started with semi-structured interviews that informed the specifications of the app, followed by an iterative design and development approach. The resulting prototype was evaluated by end-users using the perceived usefulness dimension of the technology acceptance model questionnaire. Early user engagement during the design and development of a dedicated mobile app must be taken into account to improve its perceived usefulness and future adoption.