Abstract Background In 2011, policymakers in British Columbia introduced a fee-for-service payment to incentivize infectious diseases physicians to supervise outpatient parenteral antimicrobial therapy (OPAT). Whether this policy increased use of OPAT remains uncertain. Methods We conducted a retrospective cohort study using population-based administrative data over a 14-year period (2004–2018). We focused on infections that required intravenous antimicrobials for ≥10 days (eg, osteomyelitis, joint infection, endocarditis) and used the monthly proportion of index hospitalizations with a length of stay shorter than the guideline-recommended “usual duration of intravenous antimicrobials” (LOS < UDIVA) as a surrogate for population-level OPAT use. We used interrupted time series analysis to determine whether policy introduction increased the proportion of hospitalizations with LOS < UDIVA. Results We identified 18 513 eligible hospitalizations. In the pre-policy period, 82.3% of hospitalizations exhibited LOS < UDIVA. Introduction of the incentive was not associated with a change in the proportion of hospitalizations with LOS < UDIVA, suggesting that the policy intervention did not increase OPAT use (step change, −0.06%; 95% confidence interval [CI], −2.69% to 2.58%; P = .97 and slope change, −0.001% per month; 95% CI, −.056% to .055%; P = .98). Conclusions The introduction of a financial incentive for physicians did not appear to increase OPAT use. Policymakers should consider modifying the incentive design or addressing organizational barriers to expanded OPAT use.