The lack of comprehensive health data is a significant barrier to better understanding and reducing the risk of chronic diseases among First Nations, Inuit and Métis people in Ontario. This study estimates commercial tobacco exposure (cigarette smoking and second-hand smoke) in First Nations (on- and off-reserve), Inuit and Métis in comparison to non-Aboriginal Ontarians using three health surveys. We measured age-standardized prevalence estimates using the First Nations Regional Health Survey Phase 2 (for First Nations on-reserve), Canadian Community Health Survey (for First Nations off-reserve, Métis and non-Aboriginal Ontarians) and the Aboriginal Peoples Survey (for Inuit). A higher proportion of First Nation men, women and adolescents on- and off-reserve smoked compared to their non-Aboriginal counterparts. Métis adults and adolescents were more likely to smoke than non-Aboriginal adults and adolescents. Métis adolescents were more likely to be regularly exposed to second-hand than non-Aboriginal adolescents, both at home and in public places. Inuit adults had a higher prevalence of current smoking and a higher prevalence of regular second-hand smoke exposure at home. The high prevalence of cigarette smoking and second-hand smoke exposure suggests that First Nations, Inuit and Métis people may experience a greater future burden of cancer and other chronic diseases related to smoking. Differences in survey questions and methodology, and the lack of ethnic identifiers in most Canadian health databases limit our understanding of cancer burden and other health outcomes in these populations. Knowledge-sharing and relationship building between First Nations, Inuit and Métis organizations, researchers and data custodians are essential to ensure appropriate data governance, meet health needs and further cancer control activities, including prevention.