BACKGROUND: Long-term maintenance treatment is required for patients with psoriasis. OBJECTIVES: To evaluate the efficacy and safety of guselkumab in patients with moderate to severe psoriasis through 3 years of treatment. METHODS: In 2 ongoing, phase 3 trials of guselkumab (VOYAGE 1 and VOYAGE 2), the proportions of patients achieving at least 90% and 100% improvement in the Psoriasis Area and Severity Index (PASI 90 and PASI 100, respectively) and Investigator's Global Assessment (IGA) scores of 0/1 and 0 were summarized for the guselkumab group (including placebo-to-guselkumab crossover). Patients who met treatment failure rules were considered nonresponders. Safety outcomes (rates/100 patient-years [PY]) were evaluated based on data pooled across studies through week 156. RESULTS: Three-year response rates for the guselkumab group in VOYAGE 1 and VOYAGE 2, respectively, were 82.8% and 77.2% for PASI 90, 50.8% and 48.8% for PASI 100, 82.1% and 83.0% for IGA score of 0/1, and 53.1% and 52.9% for IGA score of 0. Safety event rates across studies occurred through week 156 as follows: serious adverse events, 5.68/100 PY; serious infections, 1.15/100 PY; nonmelanoma skin cancers, 0.28/100 PY; malignancies other than nonmelanoma skin cancer, 0.47/100 PY; and major adverse cardiovascular events, 0.28/100 PY. Week 156 and week 100 rates were consistent. LIMITATIONS: There was no comparator arm beyond 1 year. CONCLUSIONS: Guselkumab shows durable efficacy and a consistent safety profile in patients with moderate to severe psoriasis treated for up to 3 years.