Aim: The incidence of factors associated with emergency cesarean section (ECS) in patients with gestational diabetes mellitus (GDM) have not been well investigated. Methods: We conducted a retrospective cohort study of patients diagnosed with GDM between 2011 and 2020 at a tertiary care hospital in Japan. Clinical data, vital signs, and laboratory results of the patients were collected from electronic medical records. We constructed a multivariate logistic regression model to identify the clinical characteristics associated with ECS. Results: We included 1189 patients diagnosed with GDM, the mean maternal age was 33 years, and 507 (42.6%) patients were aged ≥35 years. In total, 114 patients underwent ECS (9.6%). The previous assisted reproductive technology (ART) use (odds ratio [OR], 1.81; 95% confidence interval [CI], 1.12–2.93), previous artificial abortion (OR, 1.94; 95% CI, 1.13–3.33), high pre‐pregnancy body mass index (BMI) (OR, 1.07; 95% CI, 1.02–1.11), and late diagnosis of GDM (OR, 1.02; 95% CI, 1.003–1.05) were independently associated with ECS. Conclusions: One of every 10 GDM patients required ECS. Previous ART use, previous artificial abortion, high pre‐pregnancy BMI, and late diagnosis of GDM were risk factors for ECS in GDM patients. [ABSTRACT FROM AUTHOR]