Background: Nurse practitioners (NPs) are a critical part of the opioid use disorder treatment workforce. However, in states where regulations restrict NPs’ scope of practice, fewer NPs are eligible to provide this important treatment than in states where NPs have full practice authority. Purpose: To evaluate the cost-effectiveness of full practice authority relative to restricted scope of practice for NPs intending to prescribe buprenorphine for opioid use disorder in the historical context (before implementation of the Mainstreaming Addiction Treatment Act and the Medication Access and Training Expansion Act, collectively referred to as the MAT/MATE Acts) and in scenarios modeling various implementations of these acts. Methods: A simulated cohort of 10,000 NPs progressed through a decision tree model with a 1-year time horizon. Outcomes included the number of NPs prescribing buprenorphine, the number of patients treated, and the incremental cost-effectiveness ratio for both outcomes. Model inputs were sourced from existing literature. We examined uncertainty and variability in the outcomes using a probabilistic uncertainty analysis of 10,000 simulated Markov trials. Several scenarios depicting various implementations of the MAT/MATE Acts were examined, such as adoption of the Acts “as written” and increased physician prescribing. Results: In our base-case pre-MAT/MATE analysis, full practice authority produced 245 more NPs prescribing buprenorphine than restricted scope of practice (377 vs. 132) and 2,162 more patients treated (3,329 vs. 1,167) while saving $59.7 million ($0.6 million vs $60.3 million). Across 10,000 probabilistic uncertainty analysis simulations, there was a 100% probability of full practice authority being the dominant strategy (i.e., saving money while improving outcomes). These results were robust across all MAT/MATE scenarios we examined. Conclusion: Adopting full practice authority for NPs appears to be a cost-effective policy lever for increasing the available substance use treatment workforce and increasing the number of patients receiving treatment with buprenorphine.