We examined the link between discrimination and self-rated mental health (SRMH) among immigrants and Canadian-born individuals, stratified according to an individual’s identification as racialized or white. Using data from Canada’s General Social Survey (2014) (weighted N = 27,575,000) with a novel oversample of immigrants, we estimated the association of perceived discrimination with SRMH separately among immigrants and Canadian-born individuals and stratified by racialized status. Among immigrants, we also investigated whether age-at-arrival attenuated or strengthened associations. The prevalence of discrimination was higher among racialized compared to white immigrants (18.9% versus 11.8%), and among racialized compared to white non-immigrants (20.0% versus 10.5%). In the adjusted model with immigrants, where white immigrants not reporting discrimination were the referent group, both white (adjusted prevalence odds ratio [aPOR] 6.11, 95% confidence interval [CI] 3.08, 12.12) and racialized immigrants (aPOR 2.28, 95% CI 1.29, 4.04) who experienced discrimination reported poorer SRMH. The associations were weaker among immigrants who immigrated in adulthood. In the adjusted model with non-immigrants, compared to unexposed white respondents, Canadian-born white respondents who experienced discrimination reported poorer SRMH (aPOR 3.62, 95% CI 2.99, 4.40) while no statistically significant association was detected among racialized respondents (aPOR 2.24, 95% CI 0.90, 5.58). Racialized respondents experienced significant levels of discrimination compared to white respondents irrespective of immigrant status. Discrimination was associated with poor SRMH among all immigrants, with some evidence of a stronger association for white immigrants and immigrants who migrated at a younger age. For Canadian-born individuals, discrimination was associated with poor SRMH among white respondents only.