BackgroundPersistent disparities in access to mental health care for refugee and immigrant children and their families pose unique challenges to policy and practice. This study examined service provider perspectives on the barriers and opportunities for improving mental health supports for newcomer children and families in Canada.MethodsSemi-structured individual and group interviews were conducted with 33 leadership and frontline staff from 14 organizations in the health, education, settlement, and social service sectors in Hamilton, Ontario. Interview data were analyzed using the framework method.ResultsParticipants described barriers at the systems, provider, and individual and family levels that prevented newcomer families from accessing and benefiting from mental health supports. Structural barriers included inadequate services and funding, complexity of systems, cultural tensions, and, lack of prevention and early identification. Provider-level barriers included lack of representation, mental health knowledge and cultural competency, and staff shortages and burnout. Individual and family-level barriers included lack of mental health literacy, primacy of settlement needs, stigma, fear, and the high threshold for help-seeking. Participants’ recommendations for “reimagining care” related to newcomer engagement, person- and family-centered care, cultural responsiveness, mental health promotion and prevention, workforce diversity and development, collaborative and integrated care, and knowledge generation and uptake.ConclusionsThe intersection of structural, provider, and individual/family-level barriers reduce newcomer families’ access to and effectiveness of mental health supports. Reducing disparities in mental health and access to care will require a paradigm shift in the way that mental health care is conceptualized and delivered to newcomer children and families.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12913-023-09682-3.