Background: Gestational diabetes mellitus (GDM) is a subtype of diabetes that is discovered during pregnancy and may disappear after puerperium. It has an impact on the well-being of expectant mothers and fetuses. Many women have a poor level of knowledge regarding GDM, especially regarding risk factors, diagnosis, and the role of insulin in the management. Also, knowledge, attitudes, and practices regarding GDM are influenced by multiple factors.Objectives: The objective of this study was to evaluate the level of knowledge among primigravidae versus multigravidas regarding GDM. Additionally, the study sought to identify the factors that are associated with high and low levels of knowledge regarding GDM.Methodology: This is a prospective, cross-sectional study, conducted in different regions of Saudi Arabia and included 482 women who had a pregnancy history or were currently pregnant. Data were collected using a questionnaire consisting of two parts. A pilot study was carried out to evaluate the validity of the questionnaire.Results: The study data showed that a substantial portion of respondents have had one pregnancy, while there is a relatively even distribution among those with two (n=89, 18.50%), three (n=75, 15.60%), or four or more pregnancies (n=71, 14.70%). Of the participants, 65.6% had good knowledge regarding GDM. It was also found that there were significant differences between primigravidae and multigravidae.Conclusion: One-third of the participants in both groups had poor knowledge with significant variation in knowledge between primigravidae and multigravidae. The importance of screening and fasting before testing received widespread recognition, as did the role of diet and exercise in treatment. It is recommended that targeted educational efforts and awareness campaigns be launched to enhance knowledge about GDM among pregnant women in Saudi Arabia.