Background: Continuing health professions education is considered an important policy intervention for the opioid epidemic. Besides examining effectiveness or impact, it is important to also study health policy implementation to understand how an intervention was delivered within complex policy and practice environments. Implementation outcomes can be used to help interpret continuing health profession education effects and impacts, help answer questions of “how” and “why” programs work, and inform transferability.Methods: We conducted a retrospective quantitative implementation evaluation of the 2014–2017 cohort of Safer Opioid Prescribing, a Canadian continuing health professions education program consisting of three synchronous webinars and in-person workshop. To measure reach and dose, we examined participation and completion data. We used Ontario physician demographic data, including regulatory status with respect to narcotics to examine relevant trends. To measure fidelity and participant responsiveness, we analyzed participant-provided evaluations of bias, active learning and relevance to practice. We used descriptive statistics and measures of association for both continuous and categorical variables. We used logistic regression to determine predictors of workshop participation and analysis of covariance to examine variation in satisfaction across different-sized sessions.Results: Eighty four percent of participants were family physicians with representative reach to non-major urban physicians. Webinar completion rate was 86.2% with no differences in completion based on rurality, gender or status with the regulatory college. Participants who had regulatory involvement with respect to opioids were more likely to be male, have been in practice for longer and participate in the workshop. Participants reported no significant bias and highly rated both active learning and relevance to practice regardless of their cohort size.Conclusions: This evaluation demonstrates that Safer Opioid Prescribing was implemented as intended. Over a short period and without any external funding, the program reached more than 1% of the Ontario physician workforce. This suggests that Safer Opioid Prescribing is a good model for using virtual continuing health professions education to reach a critical mass of prescribers to drive population level opioid utilization changes. This study represents a methodological advance of adapting evaluation methods from health policy and complex interventions for continuing health professions education.