Abstract Background Evidence suggests that early treatment (Tx) with biologic agents in Crohn’s disease improves long-term clinical outcomes. However, there is less evidence in ulcerative colitis (UC), and data comparing early Tx with first-line biologic vedolizumab (VDZ) to anti-tumour necrosis factor (anti-TNF) in real-world settings is needed. This study compared the clinical effectiveness and safety of UC patients who initiated VDZ or an anti-TNF as a first-line biologic within 2 years following diagnosis. Methods This was a real-world, multi-country, retrospective chart review study in Canada, Greece and the United States where biologic-naïve UC patients (≥18 years old) were treated with VDZ or an anti-TNF (adalimumab, infliximab, golimumab) agent within 2 years following diagnosis (initiated Tx May 2014–March 2018). Clinical effectiveness and safety data were collected from Tx initiation to earliest of chart abstraction date, death, or 6 months post-Tx discontinuation (Canada only). Tx persistence was defined as the duration of time from treatment initiation to discontinuation. Analyses of cumulative rates of Tx persistence, clinical response, clinical remission and mucosal healing over 24 months were estimated using Kaplan–Meier analyses. Clinical response, remission and mucosal healing were assessed using pre-defined hierarchical algorithms of standard disease measures reported in the medical records. Analyses of incidence rates (per 100 person-years [PYs]) of disease exacerbations, disease-related surgeries, serious adverse events (SAEs) and serious infections (SIs) were performed. Adjusted analyses used inverse probability weighting to balance cohorts. Results This analysis included 176 UC patients (VDZ: 86; anti-TNF: 90) from 37 sites. Mean (SD) age at index date: VDZ, 41.4 (18.9); anti-TNF, 36.8 (15.6) years (p = 0.20) and the proportion male: VDZ, 58.1%; anti-TNF, 56.7% (p = 0.84). At 12 months, 72.9% and 58.1% continued VDZ and anti-TNF respectively (p = 0.03) (Figure 1A). Though there were no differences in clinical response, clinical remission or mucosal healing between VDZ and anti-TNF groups; VDZ patients were significantly less likely to experience disease exacerbations (HR = 0.47 [95% CI: 0.32–0.69]) and SAEs (HR = 0.37 [95% CI: 0.19–0.72]) (Figure 2). Adjusted outcomes (Figures 1C and D, and 2B) were similar to unadjusted outcomes. Conclusion EVOLVE is one of the first studies that compared early VDZ Tx to early anti-TNF Tx in biologic-naïve UC patients. Results showed VDZ was associated with higher persistence, lower likelihood of experiencing disease exacerbations and a more favourable safety profile. Thus, in early UC, Tx with VDZ may improve long-term clinical outcomes. Sample size limitations warrant further study.