BACKGROUND: Many states have implemented opioid days' supply restriction policies, leading to reductions in opioid prescribing. Although research within certain provider types exist, no study has evaluated a restriction policy by various provider types. OBJECTIVE: To evaluate changes in opioid utilization following a days' supply restriction policy stratified by provider type: surgery, emergency medicine, primary care, specialty care, and dentistry. DESIGN: Interrupted time series (ITS) PARTICIPANTS: Opioid prescription claims of patients in a private health plan serving a large Florida employer from 1/1/2015 to 3/31/2019. Provider types were determined using the Healthcare Provider Taxonomy Code associated with the national provider identifier (NPI). INTERVENTIONS: Florida's opioid restriction policy implemented on July 1, 2018. MAIN MEASURES: Changes in mean morphine milligram equivalent (MMEs), mean days' supply, and mean number of units dispensed per opioid prescription before and after policy implementation. KEY RESULTS: There were 10,583 opioid initial prescriptions dispensed. Treating providers were classified as surgery (16.4%; n = 1732), emergency care (14.3%; n = 1516), primary care (21.2%; n = 2241), specialty care (11.4%; n = 1207), and dentistry providers (23.7%; n = 2511). Significant reductions in mean days' supply were observed across most provider types ranging from 14% reduction for dentistry providers to 41% reduction for specialty care providers. Significant changes were observed for emergency care and specialty care providers with a 30% (p = 0.001)and 29% (p < 0.001) reduction in mean MME, respectively, and a 27% (p = 0.040) reduction in mean number of units dispensed in emergency care providers, after implementation. Pre-implementation trends in opioid prescribing varied by provider type impacting the effects of the opioid days' supply restriction policy. CONCLUSIONS: Pre-policy opioid prescribing varied by provider type with a differential impact on mean MMEs, mean days' supply, and mean number of units dispensed per prescription following implementation.