BackgroundA mobile health (mHealth) application can encourage parents and pediatric patients to be involved in caring for their child’s health condition by providing the ability to identify and actively manage chemotherapy-related symptoms in their child. Several monitoring systems available today are diverse in features and system basis. This study aimed to develop and trial the Chemo Assist for Children (CAC) mHealth application for symptom management in children with acute lymphoblastic leukemia (ALL).MethodsIn this study, the development of the CAC application went through multiple phases and methods. Study phases included: (1) development of the application’s feature based on the need assessment, (2) creation of content of application based on literature review, (3) develop prototyping of CAC, (4) expert review and feedback on the application content, (5) usability testing by targeted end-user.ResultsBased on need assessment, it was determined that parents with leukemia children were interested in symptom management of chemotherapy and preferred mobile applications. Therefore, a mHealth application was designed to include features to identify symptoms and provide recommendation strategies to manage the symptom. Usability evaluation by end-user revealed that mHealth is a valid, accessible, and appropriate application for users.ConclusionsThe CAC mHealth application developed can meet the needs of technology users to identify symptoms and manage chemotherapy-related symptoms in children with ALL. The CAC mHealth application can accommodate data not recorded at out-of-hospital care, increase the independence of symptom management, and improve communication between parents of children with ALL and health workers.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12887-023-04076-0.