Background: Knowledge of living with childhood cancer, through the trajectory, is sparse. Aim: The aim of this study was to follow young children's health and functioning in everyday life through their cancer trajectory. Methods: Data were gathered longitudinally from a group of 13 young children and their parents connected to a pediatric oncology unit in Sweden. The International Classification of Functioning, Disability and Health for Children and Youth structure was used to identify difficulties in health and functioning in everyday life, in interview and questionnaire data. Descriptive statistical analysis was performed to show patterns of difficulty over a 3-year period from diagnosis. Results: Difficulties experienced by children declined and changed over time. An increase in difficulties with personal interactions with others and access to and support from health care professionals was seen 2 to 3 years after diagnosis and start of treatment. Similar patterns are seen within individual children's trajectories in relation to diagnosis but individual patterns were seen for each child. Conclusions and Clinical Implications: Health care professionals need to plan for ongoing contact with school services and information and support pathways, beyond the treatment period. A person-centered philosophy of care is required throughout the cancer trajectory.