BACKGROUND: Patients with inflammatory bowel disease (IBD) may receive multiple successive biologic treatments in clinical practice; however, data are limited on the comparative effectiveness of biologics and the impact of treatment sequence on outcomes. METHODS: The ROTARY (Real wOrld ouTcomes Across tReatment sequences in inflammatorY bowel disease patients) study was a retrospective, observational cohort study conducted using data from the Optum Clinical Database between January 1, 2012, and February 29, 2020. Adult patients with Crohn's disease (CD) or ulcerative colitis (UC) who received 2 biologics successively were included. Biologic treatment sequences were analyzed descriptively. Cox proportional hazards models, adjusted for baseline demographics and clinical characteristics, were used to estimate the hazard ratio of switching or discontinuation for each first- and second-line biologic compared with first- and second-line adalimumab, respectively. RESULTS: In total, 4648 patients with IBD (CD, n = 3008; UC, n = 1640) were identified. Most patients received tumor necrosis factor α antagonist (anti-TNFα) treatment followed by another anti-TNFα treatment or vedolizumab. Vedolizumab and infliximab had 39.4% and 34.6% lower rates of switching or discontinuation than adalimumab, respectively, as first-line biologics in patients with CD and 30.8% and 34.3% lower rates as first-line biologics in patients with UC, respectively. Vedolizumab, infliximab, and ustekinumab had 47.2%, 40.0%, and 43.5% lower rates of switching or discontinuation than adalimumab, respectively, as second-line biologics in CD and 56.5%, 43.0%, and 45.6% lower rates as second-line biologics in patients with UC, respectively. CONCLUSIONS: Although anti-TNFα treatments were most commonly prescribed, the adjusted rates of discontinuation for adalimumab as both a first- and second-line biologic were higher than for vedolizumab, infliximab, or ustekinumab.