Accessible SummaryWhat is known on the subject? Family‐involved interventions can result in better outcomes than traditional mental health care for both service users and their families. Nurses' attitudes towards family involvement can affect family participation in care. Earlier studies on psychiatric nurses' attitudes towards family involvement in care report ambiguous findings. Hong Kong's unique integrated cultures may influence Hong Kong psychiatric nurses' attitudes towards family involvement in nursing care. What the paper adds to existing knowledge? The majority of psychiatric nurses had positive views on family involvement in care in Hong Kong. Four variables (i.e. gender, clinical experience, nature of working unit and family nursing training) of psychiatric nurses are associated with their attitudes towards family involvement in care in Hong Kong. What are the implications for practice? Policy makers should develop strategies to increase psychiatric nurses' awareness of the importance of family involvement in patient care. Nurse educators help to design family nursing training to enhance psychiatric nurses' competence in collaborating with families of people suffering from mental disorders. AbstractIntroductionIn Hong Kong, involving the family in nursing care is still optional and mainly depends on nurses' attitudes and the willingness of the family. Hong Kong psychiatric nurses' attitudes towards family involvement in nursing care may be influenced by the unique integrated Eastern and Western cultures, however earlier studies report ambiguous findings.AimsThis study aimed to assess Hong Kong psychiatric registered nurses' attitudes towards family involvement in care and its associated factors.MethodsThis study is a cross‐sectional descriptive online survey with convenience sampling based on the Families' Importance in Nursing Care‐Nurses' Attitudes (FINC‐NA) instrument.ResultsMost of the psychiatric nurses had supportive attitudes towards family involvement in care. Females with more clinical experience, working in a rehabilitation‐related unit and having attended a family nursing education course were associated with positive attitudes towards family involvement in care.DiscussionThe supportive attitude of psychiatric nurses may be explained by the shift of mental health nursing care from hospital care to community care in recent decades.Implications for practiceMental health nurse education and training in Hong Kong could place more emphasis on building family work skills, particularly for newly qualified nurses and those working in acute inpatient settings.