BACKGROUND: Paediatric critical care (PCC) is a high-pressure working environment. Staff experience high levels of burnout, symptoms of post-traumatic stress, and moral distress. AIM: To understand challenges to workplace well-being in PCC to help inform the development of staff interventions to improve and maintain well-being. STUDY DESIGN: The Enhanced Critical Incident Technique (ECIT) was used. ECIT encompasses semi-structured interviews and thematic analysis. We identified 'critical incidents', challenges to well-being, categorized them in a meaningful way, and identified factors which helped and hindered in those moments. Fifty-three nurses and doctors from a large UK quaternary PCC unit were consented to take part. RESULTS: Themes generated are: Context of working in PCC, which examined staff's experiences of working in PCC generally and during COVID-19; Patient care and moral distress explored significant challenges to well-being faced by staff caring for increasingly complex and chronically ill patients; Teamwork and leadership demonstrated the importance of team-belonging and clear leadership; Changing workforce explored the impact of staffing shortages and the ageing workforce on well-being; and Satisfying basic human needs, which identified absences in basic requirements of food and rest. CONCLUSIONS: Staff's experiential accounts demonstrated a clear need for psychologically informed environments to enable the sharing of vulnerabilities, foster support, and maintain workplace well-being. Themes resonated with the self-determination theory and Maslow's hierarchy of needs, which outline requirements for fulfilment (self-actualization). RELEVANCE TO CLINICAL PRACTICE: Well-being interventions must be informed by psychological theory and evidence. Recommendations are flexible rostering, advanced communication training, psychologically-informed support, supervision/mentoring training, adequate accommodation and hot food. Investment is required to develop successful interventions to improve workplace well-being.