Background/Aims: We investigated the real-world effectiveness and safety of ustekinumab (UST) as induction treatment for Koreans with Crohn’s disease (CD).Methods: CD patients who started UST were prospectively enrolled from 4 hospitals in Korea. All enrolled patients received intravenous UST infusion at week 0 and subcutaneous UST injection at week 8. Clinical outcomes were assessed using Crohn’s Disease Activity Index (CDAI) scores at weeks 8 and 20 among patients with active disease (CDAI ≥150) at baseline. Clinical remission was defined as a CDAI <150, and clinical response was defined as a reduction in CDAI ≥70 points from baseline. Safety and factors associated with clinical remission at week 20 were also analyzed.Results: Sixty-five patients were enrolled between January 2019 and December 2020. Among 49 patients with active disease at baseline (CDAI ≥150), clinical remission and clinical response at week 8 were achieved in 26 (53.1%) and 30 (61.2%) patients, respectively. At week 20, 27 (55.1%) and 35 (71.4%) patients achieved clinical remission and clinical response, respectively. Twenty-seven patients (41.5%) experienced adverse events, with serious adverse events in 3 patients (4.6%). One patient (1.5%) stopped UST therapy due to poor response. Underweight (body mass index <18.5 kg/m²) (odds ratio [OR], 0.085; 95% confidence interval [CI], 0.014–0.498; <i>P</i>=0.006) and elevated C-reactive protein at baseline (OR, 0.133; 95% CI, 0.022–0.823; <i>P</i>=0.030) were inversely associated with clinical remission at week 20.Conclusions: UST was effective and well-tolerated as induction therapy for Korean patients with CD.