The concurrence of health insurance expansion under the Affordable Care Act (ACA) and increasing opioid‐related mortality has led to debate whether insurance increases or decreases opioid deaths. I use the introduction of the ACA young adult (YA) provision as a quasi‐experiment and utilize the resulting policy‐induced variation across states over time in YA access to insurance to study the effect of coverage on opioid‐related mortality. I rely on the share of state populations which stood to gain insurance before the ACA to perform a dose–response analysis, and find that the YA provision reduced opioid‐related mortality. The analysis suggests that 1 percentage point more coverage reduced opioid mortality among YA by 2.5/100,000 or 19.8%.