There is a growing need for healthcare professionals to ensure that their practices are inclusive and that they are considerate of the needs of marginalized communities. Inclusion health (IH) seeks to correct the imbalances that result in health inequities and requires health practitioners to have an adequate understanding and knowledge of the needs of marginalized and vulnerable population groups. The aim of this systematic review was to synthesize and critically appraise evidence from studies that explored healthcare professionals' knowledge and/or awareness of IH. Academic Search Complete, CINAHL Plus with Full Text, MEDLINE, APA PsycArticles, APA PsycInfo, and SocINDEX were systematically searched without any year or language limits. The last search was conducted on 16 December 2024. A total of 4870 studies were identified, of which 37 were included (21 qualitative studies, 7 quantitative studies, 6 mixed-methods studies, 2 cross-sectional studies, and 1 quasi-experimental study). The methodological quality of the studies was appraised. Most studies were from the USA and Australia and focused on IH knowledge regarding members of the lesbian, gay, bisexual, trans, and queer community, people with disabilities, and culturally diverse populations. Studies examining healthcare professionals' knowledge and awareness were not homogenous in nature resulting in a wide variety of studies and types of data. Different minority groups require varied levels of insight and understanding from their healthcare professionals. There is therefore no one-size-fits-all solution. We recommend targeted interventions throughout the training and education of healthcare professionals, informed and designed by the participation of members of those marginalized communities.