People with serious mental illness (SMI) have increased risk of cardiovascular disease and premature death, yet research on nurse-provided health promotion in mental health services remains under-developed. This paper informs efforts to improve the nursing role in physical health of consumers with SMI by establishing what nurse perceptions and background influence their care. Members of the Australian College of Mental Health Nursing were invited to participate in an online survey on their views on physical health care in mental health services. Survey questions included: (a) nurse-consumer collaboration in preventative care and (b) sub-sections of the Robson and Haddad Physical Health Attitude Scale to measure nurse perceived barriers to encouraging lifestyle change of consumers with SMI and frequency of nurse physical healthcare practices. Structural equation modelling was applied to investigate antecedents to physical health care, as well as relationships between antecedents. A national sample of 643 nurses reported regular engagement in health promotion (e.g. advice on diet). There was statistical support for a model depicting perceived consumer-nurse collaboration as a dual-determinant of nurse perceived barriers and self-reported health promotion to consumers with SMI. Perceived barriers to consumer lifestyle change did not predict health promotion. The effects of nurse-consumer collaboration were significant, but small. Perceived consumer-nurse collaboration in preventative care may positively influence the amount of health promotion by nurses in mental health. Perceived barriers to consumer adherence with a healthy lifestyle did not have an impact on nurse-delivered health promotion.