Objective Stigma is commonly identified as a key reason that older adults are especially unlikely to seek mental health services, although few studies have tested this assumption. Our objectives were to: (a) examine age differences in public and self‐stigma of seeking help, and attitudes toward seeking help, and (b) see whether age moderates an internalized stigma of seeking help model. Methods A total of 5,712 Canadians ranging in age from 18 to 101 completed self‐report measures of public stigma of seeking help, self‐stigma of seeking help, and help‐seeking attitudes. Results Older participants had the lowest levels of stigma and the most positive help‐seeking attitudes. Age also moderated the mediation model, such that the indirect effect of public stigma on help‐seeking attitudes through self‐stigma was strongest for older participants. Conclusion Our findings have implications for the influence of stigma and attitudes as barriers to treatment across the adult lifespan, and for stigma reduction interventions.