In the United Kingdom, the prevalence of children and young people (CYP) accessing acute paediatric inpatient care with mental health problems is increasing, with self-harm and eating disorders particularly prevalent. This study evaluated CYP experiences of being in receipt of acute paediatric inpatient care following either self-harm or crisis stemming from an eating disorder to inform domains for a person-centred outcome measure (PCOM). A series of stakeholder engagement events were conducted between April and July 2015 where creative approaches were used to explore stakeholder experiences of care and to identify outcome domains that were subsequently prioritised using a Nominal Group Technique. Data were analysed using inductive thematic approach, with significance scores calculated for domain statements. Ninety-six stakeholders (15 CYP, eight parents and carers, and 73 professionals) participated. Findings showed five priority PCOM domains: privacy and surveillance; holistic care; making choices, appropriate communication; working together to achieve care goals; and respect and empowerment. This single centre evaluation highlights the need for a PCOM to be developed for this patient group that comprehensively reflects stakeholders' expectations in order to inform improvements to quality of acute paediatric care.