Background: Pregnant mothers and their fetuses are at risk of developing gestational diabetes (GDM) which is a serious health issue. Individuals' literacy levels significantly impact their decision-making and lifestyle practices, which in turn have an impact on managing and preventing persistent diseases like diabetes .The aim of the study was to evaluate the effect of educational intervention based on a health literacy model on knowledge and lifestyle among women with gestational diabetes. Research design: Quazi experimental design was used to conduct the present study. Setting: The study was carried out at Zagazig University Hospital's outpatient clinics at the antenatal care unit. Subjects: Purposive sample of 90 pregnant women with gestational diabetes. Tools of data collection: Three tools were used for data collection. Tool I: A structured interviewing questionnaire; Tool II: Self-administered Health Literacy Questionnaire (HLQ); and Tool III: Health Promotion Lifestyle Profile Scale (HPLP). Results: The study revealed a significant improvement in all subscales of women's knowledge, health literacy and health promotion lifestyle, with a highly statistically significant difference (p < 0.01). Additionally, a highly statistically significant positive correlation was found between total women's knowledge score, total health literacy and total health promotion lifestyle score at pre and post implementation of the educational intervention (p = 0.000).Conclusion: It was concluded that the investigated women's total knowledge, health literacy, and health promotion lifestyles improved significantly after the intervention. Recommendations: Incorporating health literacy principles alongside traditional maternity care services is essential for effectively managing gestational diabetes.