OBJECTIVE: To determine if engagement in office-based opioid treatment decreases emergency department, urgent care visits, and hospitalizations for acute opioid-related events (OREs) among adolescents with opioid use disorder. STUDY DESIGN: This retrospective cohort study identified all emergent and outpatient visits among adolescents, age 10-19 years, referred for office-based opioid treatment between January 1, 2006 and December 31, 2016. Patients were dichotomized into 2 cohorts: those who did and did not engage in office-based opioid treatment. The primary end point was the difference in the proportion of visits over the study period for acute OREs between cohorts and within the office-based opioid treatment cohort before and after referral. Secondary end points assessed change in the proportion of outpatient visits for treatment unrelated to opioid use disorder. RESULTS: Four hundred five emergent and outpatient visits were identified: 285 (70.4%) in the office-based opioid treatment cohort and 120 (29.6%) in the non-office-based opioid treatment cohort. After office-based opioid treatment engagement, 27.8% of visits in the office-based opioid treatment cohort were for acute OREs vs 80.8% in the non-office-based opioid treatment cohort (OR, 0.092; 95% CI, 0.052-0.160; P < .001). Outpatient visits in the office-based opioid treatment cohort were 10.9 times that of non-office-based opioid treatment (OR, 10.9; 95% CI, 6.23-19.16; P < .001). Within the office-based opioid treatment cohort, emergent visits decreased from 76.1% to 27.8% (OR, 0.121; 95% CI, 0.070-0.210; P < .001) and the odds of outpatient services was 8.3 times more after engagement (OR, 8.27; 95% CI, 4.78-14.4, P < .001). CONCLUSIONS: The absolute decrease in emergent visits for acute OREs was 53% in adolescents engaged in office-based opioid treatment, representing a relative decrease of 65.6% compared with adolescents not engaged. An analysis of visits before and after office-based opioid treatment demonstrated similar decreases, suggesting that office-based opioid treatment has a significant impact in decreasing acute OREs in the adolescent population.