Certolizumab pegol (CZP) is an Fc-free, PEGylated anti-tumour necrosis factor biologic.Report three-year safety from three phase 3 trials of CZP in adults with plaque psoriasis (PSO).Data were pooled from CIMPASI-1 (NCT02326298), CIMPASI-2 (NCT02326272), CIMPACT (NCT02346240). Included patients: had moderate to severe PSO ≥6 months; were randomised to CZP 200 mg every two weeks (Q2W) (400 mg at Weeks 0, 2, 4) or CZP 400 mg Q2W; received ≥1 dose CZP with up to 144 weeks' exposure. Treatment-emergent adverse events (TEAEs) were classified using MedDRAv18.1. Reported incidence rates (IRs) are incidence of new cases/100 patient-years (PY).Over 144 weeks, 995 patients received ≥1 dose CZP (exposure: 2,231.3 PY); 731 and 728 received ≥1 dose CZP 200 mg Q2W (1,211.4 PY) and 400 mg Q2W (1,019.9 PY), respectively. IR (95% confidence interval [CI]) of TEAEs was 144.9 (135.3-155.0) for all patients; 134.1 (123.2-145.7) and 158.3 (145.5-171.9) for CZP 200 mg and 400 mg Q2W, respectively. IR of serious TEAEs for all patients was 7.5 (6.4-8.8); 6.7 (5.2-8.3) and 8.7 (6.9-10.8) for CZP 200 mg and 400 mg Q2W, respectively. 3.2% patients reported serious infections (2.2% within each of the CZP 200 and 400 mg Q2W groups). Overall, there was 1 case of active tuberculosis, 16 malignancies in 14 patients and 7 deaths (2 considered treatment-related). Cumulative IR of TEAEs did not increase over time.No new safety signals were identified compared to previously reported data. Risk did not increase with longer or higher CZP exposure.