BackgroundCancer treatment for children is typically long-term and difficult, and the experience is unique for each child. When designing child-centred care, individuals’ values and preferences are considered equally important as the clinical evidence; therefore, understanding children’s thoughts and attitudes while they receive long-term treatment could offer valuable insights for better clinical practice.MethodsWe conducted long-term consecutive participatory observations and interviews with seven children, who were hospitalised and receiving cancer treatment for the first time. The daily observational data on those children’s discourses, behaviours and interactions with health professionals were systematically collected and thematically examined. The analysis was expanded to explore significant narratives for each child to capture their narrative sequence over time.ResultsThe initial analysis identified 685 narrative indexes for all observation data, which were categorised into 21 sub-codes. Those sub-codes were assembled into five main themes by thematic analysis: making promises with health professionals, learning about the treatment procedures through participation, taking care of oneself, increasing the range of activities one can perform and living an ordinary life.ConclusionWe observed a forward-looking attitude toward understanding cancer, accepting treatment and looking forward to the future among children undergoing in-hospital cancer treatment. In addition, the children developed cognitively, affectively and relationally throughout cancer treatment processes. These findings have implications for better clinical practice in child-centred care, including children’s participation in shared decision-making in paediatric oncology.