<p>Roma and Traveller communities are among the most historically and systemically excluded ethnic groups, experiencing substantially poorer health-related quality of life than mainstream populations and disproportionate rates of suicide. While they share common experiences of marginalisation and are often grouped in legislation, Roma and Traveller groups encompass a heterogenous set of communities with distinct cultural identities that should be appropriately reflected in the design and delivery of mental health services. This rapid review identifies key considerations for culturally competent mental health care and provides evidence-informed directions to guide service development. Peer-reviewed articles related to indigenous mental health published between 2015 and 2025 were identified using an adapted PICO framework. Searches were conducted within PsychInfo and Academic Search Complete, yielding 2815 records, of which 31 articles met the criteria for inclusion and analysis. Across the literature, three core themes were identified: (i) cultural awareness, (ii) collaborative health partnerships, and (iii) social determinants. The thematic synthesis of the empirical evidence reinforces the value of lived experience input into all stages of service design from conceptualisation to delivery and identifies several critical factors for creating cultural competence in mental health services, including trust building, promoting health literacy through inclusive education, and social participation in research and practice.</p>