This study aimed to develop a website providing physiotherapy, exercise, and disease knowledge information as a digital tool for use in children with chronic suppurative lung diseases (CSLDs). Data were analyzed using a mixed qualitative and quantitative approach. Initially, a comprehensive list of the website’s content and functions was developed through a focus group study with healthcare professionals (HCPs) and parents. Afterward, two rounds online Delphi survey were conducted with a group of expert HCPs (pediatricians and physiotherapists) who were recruited based on their expertise in the field of pediatric physiotherapy. The focus groups established 10 main themes. Two rounds of Delphi questionnaires established the important items of a website, based on expert consensus from HCPs. A Delphi survey containing 36 outcomes was completed by participants from Greece. The findings support the integration of multidisciplinary and user-centered approaches in the design of pediatric website. This website is expected to enhance disease self-management, improve treatment adherence, and support families in daily care.