This study assessed the impact of electronic health record (EHR) interventions to standardize opioid prescribing practices across a large health system. Interventions included (1) deleting clinician preference lists, (2) default dose, frequency, and quantity, (3) standardizing formularies, and (4) dashboards with current opioid prescribing practices. In the 12 months after implementation, there was a decrease in the rate of opioid prescriptions overall, prescriptions exceeding three days, prescriptions exceeding prespecified morphine equivalent doses, and non-formulary prescriptions.