Background <p>Against the backdrop of a severe drug toxicity crisis, this study examined socioeconomic inequities in drug poisoning mortality among working-age adults in Canada.</p> Methods <p>We conducted a population-based cohort study using the 2016 Canadian Census Health and Environment Cohort (<i>n</i> = 4,588,745). Census respondents aged 25–64 were linked to mortality records for the period 2016–2021. We used Poisson regression models to estimate rate ratios and rate differences in drug poisoning deaths by education, household income, and employment status. Analyses were conducted separately for women and men, adjusting for various sociodemographic factors.</p> Results <p>The crude rate of drug poisoning mortality was 8.7 and 17.5 deaths per 100,000 person-years among women and men, respectively. We observed pronounced inequities in drug poisoning mortality according to education, household income, and employment status. For example, among women and men, respectively, rates of drug poisoning mortality were 7.55 (95% CI, 6.73–8.36) and 7.70 (95% CI, 7.01–8.39) times higher among individuals without a high school degree (compared to university graduates), 6.70 (95% CI, 5.96–7.44) and 4.60 (95% CI, 4.27–4.93) times higher among individuals in the lowest quintile of household income (compared to the highest earners), and 5.58 (95% CI, 4.94–6.22) and 3.56 (95% CI, 3.32–3.80) times higher among unemployed individuals (compared to full-time workers).</p> Conclusion <p>The findings draw attention to persistent socioeconomic inequities in drug poisoning deaths among working-age adults in Canada. Interventions are urgently needed to address the growing drug toxicity crisis, as well as socioeconomic inequities therein.</p>