Background Health care focus is shifting for children from surviving childhood cancer to living with it on a daily basis. There is a need to document health and function in the everyday lives of young children with cancer using the multidimensional framework and language of the International Classification of Functioning, Disability and Health – Children and Youth (ICF-CY). Aims The aims of this study were (1) to document health and functioning in the everyday lives of young children with cancer using ICF-CY codes and (2) to identify a comprehensive code set that can aid clinical assessment. Method Interviews with children diagnosed with cancer and their parents, were transcribed, reviewed for content and coded to the ICF-CY using linking procedures. Results A comprehensive code set (n = 70) for childhood cancer was identified. The majority of content identified to codes was related to activity and participation describing social relations with family, peers and professionals, preschool attendance and play, as well as issues related to support and independence. Conclusions The ICF-CY can be used to document the nature and range of characteristics and consequences of cancer experienced by children. The identified comprehensive code set could be helpful to health care professionals, parents and teachers in assessing and supporting young children’s health and everyday life through the cancer trajectory. The comprehensive code set could be developed as a clinical assessment tool for those caring for young children with cancer. The universal language of the ICF-CY means that the utility of a clinical assessment tool based on identified codes can have wide reaching effects for the care of young children with cancer.