BackgroundGlobally, the prevalence of gestational diabetes mellitus (GDM) is currently rising. Assessing GDM knowledge and taking various public health actions will help pregnant women know more about the condition, resulting in its prevention.ObjectiveTo assess pregnant women’s knowledge of GDM and associated factors at antenatal care clinics of public hospitals in the North Shewa zone, Oromia region, Central Ethiopia.DesignCross-sectional study.SettingFive public hospitals of North Shewa zone, Oromia regional state, Central Ethiopia.ParticipantsA total of 417 pregnant women.MethodsA face-to-face interview was conducted. A 13-items tool was used to measure GDM knowledge. Multivariable binary logistic regression was fitted to identify factors associated with the knowledge of GDM. The adjusted OR (AOR) with 95% CI and a p<0.05 was used to determine statistical significance.ResultsOverall, 48% (95% CI 43.4% to 52.8%) of pregnant women had sufficient knowledge about GDM. The level of sufficient knowledge for GDM risk factors, screening/treatment and its consequences were 48%, 54.4% and 99%, respectively. Age group 15–24 years (AOR 3.49, 95% CI 1.05 to 11.59), attending secondary and above education (AOR 4.27, 95% CI 1.29 to 14.070, women whose partners attended primary school (AOR 3.83, 95% CI 1.36 to 10.78), history of GDM (AOR 3.36, 95% CI 1.68 to 6.71), history of hypertension (AOR 2.42, 95% CI 1.21 to 4.84), receiving preconception care (AOR 3.02, 95% CI 1.74 to 5.22) and being multigravida (AOR 3.19, 95% CI 1.52 to 6.67) were factors significantly associated with sufficient knowledge about GDM.ConclusionOverall, more than half of pregnant women have insufficient knowledge about GDM. Significant association between GDM knowledge and women’s age, women’s and partners’ educational status, preconception care, history of GDM and hypertension, and the number of pregnancies were detected. Therefore, to increase pregnant women’s GDM knowledge, health education programmes in the community and healthcare facilities should target the identified factors.