PurposeThis study aimed to understand the experience of families caring for a child with cancer in New Zealand (NZ) who received nutrition and dietetic support during cancer treatment and their preferences for the delivery, format, and timing of nutrition information.MethodsChildhood cancer patients and their families (N= 21) participated in a mixed-methods study at a specialist paediatric oncology centre in Auckland, NZ. Before the semi-structured interview, participants completed a questionnaire capturing demographic, disease, and treatment characteristics of their child, their nutrition concerns, and their information needs. Quantitative data were described, and qualitative thematic analysis of the semi-structured interviews was performed using NVivo data analysis software.ResultsEighty-six percent of participants indicated they had concerns about their child’s nutrition during treatment. The most common concerns were anorexia, vomiting, and weight loss. While many were happy with the quality of the nutrition support received, one-third of the patients wanted more support. Four key themes emerged from the interviews: (1) patients experience significant and distressing nutrition challenges; (2) patients and families have mixed perceptions of EN; (3) there are gaps in the current nutrition support system for inpatients; and (4) a desire for more accessible nutrition support.ConclusionChildhood cancer patients and families experience significant and distressing nutrition challenges during treatment. Standardising information given to patients and their families may optimise nutrition support for paediatric oncology patients and reduce the discordance between families and health professionals. Future implementation of a nutrition decision aid in this population is warranted.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00520-023-07787-3.