Mental health professionals’ attitudes toward offenders with mental illness have significant implications for the quality of care and treatment rendered, making it imperative for these professionals to be aware of their attitudes. Yet, this topical issue has received little research attention. Consequently, the present study investigates attitudes toward offenders with mental illness (insanity acquittees) in a sample of 113 registered mental health nurses in Ghana. Using a cross-sectional survey and self-report methodology, the participants respond to measures of attitudes toward offenders with mental illness, attitudes toward mental illness, conviction proneness, and criminal blameworthiness. The results show that mental health nurses who reportedly practiced for a longer duration (6 years and above) were more likely to be unsympathetic, while the male nurses who were aged 30 years and above were more likely to hold offenders with mental illness strictly liable for their offenses. Importantly, the nurses’ scores in conviction proneness and criminal blameworthiness significantly predict negative attitudes toward the offenders even after controlling for their attitudes toward mental illness. Yet, when the nurses’ conviction proneness and criminal blameworthiness were held constant, their attitudes toward mental illness failed to predict attitudes toward the offenders. This initial finding implies that the nurses’ views regarding criminal blameworthiness and conviction may be more influential in understanding their attitudes toward offenders with mental illness relative to their attitudes toward mental illness.