BACKGROUND: Dual diagnosis is a global health concern. This descriptive research assessed mental health nurses' attitudes towards consumers with dual diagnosis in Australian mental health settings. The research question was: What is the attitude of mental health nurses towards consumers with co-existing mental health and drug and alcohol problems? This cross-sectional survey included 103 mental health nurses who work with consumers with dual diagnosis. Participants were recruited from various mental health settings through convenience sampling. The Comorbidity Problems Perceptions Questionnaire was used to assess attitudes. Descriptive data and multiple regression analyses were conducted. We utilized the consensus-based checklist for reporting results of this study. Mental health nurses positively perceived consumers with dual diagnosis. Factors associated with a positive attitude were a higher level of work experience, feeling that one's role is adequate, perceiving one's role as legitimate, receiving increased support in one's position, having high work motivation, possessing high task-specific self-esteem and experiencing higher levels of work satisfaction. Work experience predicted role adequacy. Position predicted role support. The work sector predicted role-related self-esteem. As mental health nurses gain work experience; they develop positive attitudes that boost their self-esteem and sense of importance towards consumers with dual diagnosis. This constructive mindset also positively affects their work motivation and job satisfaction towards consumers with dual diagnosis. Conducting interventional studies is necessary to examine how clinical experiences, work environments, and job positions can impact attitudes, aiming to improve mental health nursing interventions towards consumers with dual diagnosis. The study found that mental health nurses' positive attitudes towards consumers with dual-diagnosis are influenced by their experience and knowledge. Moreover, mental health nurses who feel supported, motivated and confident in their roles are more likely to provide high-quality care to consumers with dual diagnosis. Mental health nurses could provide better care and support if they took a proactive approach and addressed the challenges associated with this consumer population. To be successful in their roles, mental health nurses require access to resources and support from healthcare organizations. As a result, their job satisfaction and attitudes towards consumers with dual diagnosis will be enhanced. In this way, consumers as well as healthcare organizations will benefit.