Background Patients receiving acute haemodialysis treatment and living with severe mental illness may display behaviours that are perceived as challenging and stressful for renal nurses to manage in the acute haemodialysis unit. Renal nurses are historically trained on the technical aspects of acute haemodialysis and can provide a level of psychological support to patients. However, they have not been trained to manage patients with severe mental illness. Objective To explore renal nurses' experiences of nursing patients with severe mental illness receiving acute haemodialysis, and to identify factors that facilitate or hinder the nursing care of these patients. Design A descriptive qualitative study. Method Purposive sampling was employed, and semi‐structured interviews were conducted with 10 renal nurses working in an acute haemodialysis unit. Thematic analysis was utilised to analyse the data. Findings Thematic analysis identified four main themes which are perspectives of mental Illness, patient and staff safety concerns, facilitators of care and education and support needs. Conclusion Renal nurses experienced difficulty managing challenging behaviours manifested by patients with severe mental illness. Despite the various challenges, renal nurses adopted a person‐centred approach. Staff shortages and lack of training were significant hindrances to care delivery. Education on mental health conditions, support from senior staff and collaborative working can enable confidence and increase renal nurses' knowledge and experience in mental health care.