IntroductionOptimal outcomes during childhood cancer treatment require effective management of toxicities, often called supportive care. A lack of agreement on what comprises supportive care limits the development and provision of comprehensive guidance (for this work, we have defined supportive care as any disease‐ or treatment‐related condition experienced by children with cancer, excluding psychosocial conditions, palliative care, survivorship, or procedural topics). To address this gap, we conducted a consensus‐building exercise among global experts to define and prioritize topics for supportive care.MethodsTwo rounds of brainstorming and prioritization exercises were conducted. A multidisciplinary panel nominated by professional societies and cooperative groups was formed to ensure geographic and resource representation using snowball sampling. An internal expert panel generated an initial list of supportive care topics. In round one, the multidisciplinary panel reviewed the initial list and recommended additional topics, followed by prioritization in round two using a seven‐point Likert scale. Results were summarized using descriptive statistics.ResultsThe multidisciplinary panel consisted of 57 members representing 32 countries. The initial list included 46 topics; 161 additional topics were suggested. After removing duplicates and out‐of‐scope additions, the final list contained 62 topics. Febrile neutropenia, sepsis, bloodstream infections, and pain were ranked highest priority. Mortality, morbidity, and frequency of the event were identified as the most important factors influencing prioritization.ConclusionThrough a multidisciplinary and globally representative process, we identified core supportive care topics and factors influencing their prioritization for childhood cancer. Outputs from this work will inform efforts to generate resource‐adapted recommendations for a global audience. This supports ongoing WHO CureAll work to develop a health systems‐level policy brief of supportive care requirements in the management of children with cancer.