Abstract Objective To assess the impact of Florida’s 3-day opioid prescription supply law, effective July 2018, on opioids dispensed for acute pain patients. Methods Pharmacy claims from a health plan serving a large Florida employer from January 2015 through March 2019 were analyzed. We used an interrupted time series study design accounting for autocorrelation of trends before and after policy change. Acute pain patients met inclusion criteria if they had not received any opioid containing medications in the past 180 days. Patients could contribute to additional new use time if subsequent opioid claims occurred ≥180 days since the previous claim. Outcomes included mean number of units dispensed of the initial opioid prescription, mean morphine milligram equivalents (MMEs) per day of initial prescription by month, and mean total MMEs per initial prescription by month. Results A total of 8,375 enrollees had 10,583 unique opioid starts in the given timeframe. Following the policy, there was an immediate significant decrease in the units dispensed per prescription of 4.9 (95% confidence interval [CI] −8.95, −.82 units). Additionally, there was a significant immediate reduction in total MMEs dispensed per prescription of 25.6 (95% CI −44.76, −6.44 MMEs). Conclusions Among a group of privately-insured plan enrollees in Florida, and as a result of the law, there were significant decreases in the number of units dispensed, and total MMEs of opioid prescriptions. The immediate reduction in new opioid utilization following policy implementation suggests effective policy; however, impacts on chronic pain patients were not assessed.