Abstract Background People with cancer are at high risk of malnutrition. Nutrition education is an effective strategy to improve patient outcomes, however, little is known regarding the impact of family and/or carer involvement in nutrition education and requires investigation. The purpose of the study was to evaluate PIcNIC (Partnering with families to promote nutrition in cancer care) intervention acceptability from the perspective of patients, families and health care providers. Methods A descriptive qualitative study was undertaken at an inpatient and an outpatient hospital setting in Australia and an outpatient/home setting in Hong Kong. A patient-and-family centred intervention including nutrition education, goals setting/nutrition plans, and food diaries, was delivered to patients and/or families in the inpatient, outpatient or home setting. Semi-structured interviews were used to explore perceptions of the intervention. 64 participants were interviewed; 20 patients, 15 family members, and 29 health care professionals. Data were analysed using deductive and inductive content analysis. Results Two categories were identified; 1) ‘context and intervention acceptability’; and 2) ‘benefits of patient- and family-centred nutrition care’. Within each category redundant concepts were identified. For category 1 the redundant concepts were: the intervention works in outpatient settings, the food diary is easy but needs to be tailored, the information booklet is a good resource, and the intervention should be delivered by a dietitian, but could be delivered by a nurse. The redundant concepts for category 2 were: a personalised nutrition plan is required, patient and family involvement in the intervention is valued and the intervention has benefits for patients and families. Converging and diverging perceptions across participant groups and settings were identified. Conclusions In this paper we have described an acceptable patient- and family-centred nutrition intervention, which may be effective in increasing patient and family engagement in nutrition care and may result in improved nutrition intakes. Our study highlights important contextual considerations for nutrition education; the outpatient and home setting are optimal for engaging patients and families in learning opportunities.