Aims To examine the efficacy and safety of once‐weekly dulaglutide monotherapy (0.75 mg) compared with placebo and once‐daily liraglutide (0.9 mg) in Japanese patients with type 2 diabetes. Methods This was a phase III, 52‐week (26‐week primary endpoint), randomized, double‐blind, placebo‐controlled, open‐label comparator (liraglutide) trial comparing 492 Japanese patients with type 2 diabetes (dulaglutide, n = 281; liraglutide, n = 141; and placebo, n = 70) who were aged ≥20 years. Patients and investigators were blinded to treatment assignment for dulaglutide and placebo but not for liraglutide. The primary objective evaluated the superiority of dulaglutide versus placebo on change from baseline in glycated haemoglobin (HbA1c) at 26 weeks. Analyses were performed on the full analysis set. Results At 26 weeks, once‐weekly dulaglutide was superior to placebo and non‐inferior to once‐daily liraglutide for HbA1c change from baseline least squares mean difference: dulaglutide vs placebo −1.57% (95% confidence interval −1.79 to −1.35); dulaglutide vs liraglutide −0.10% (95% confidence interval −0.27 to 0.07). The most frequently reported adverse events were nasopharyngitis, constipation, diarrhoea, nausea, abdominal distension and decreased appetite; only decreased appetite was different between the dulaglutide and liraglutide groups dulaglutide, n = 2 (0.7%); liraglutide, n = 8 (5.8%); p = 0.003. Nine (1.8%) patients experienced hypoglycaemia dulaglutide, n = 6 (2.1%); liraglutide, n = 2 (1.5%); placebo, n = 1 (1.4%), with no event being severe. Conclusions In Japanese patients with type 2 diabetes, once‐weekly dulaglutide (0.75 mg) was superior to placebo and non‐inferior to once‐daily liraglutide (0.9 mg) for reduction in HbA1c at 26 weeks. Dulaglutide was safe and well tolerated.