OBJECTIVE: Hyperglycemic mothers and their offspring are at increased risk of various maternal and neonatal complications such as macrosomia, future type 2 diabetes, and metabolic abnormalities. Early diagnosis and individualized dietary management, exercise, and emotional well-being are expected to reduce these risks. The study aims to identify the effect of the Nutrition and Behavior Modification Program (NBMP) on maternal and neonatal outcomes of hyperglycemic mothers. PATIENTS AND METHODS: A pre-experimental study was performed among 89 hyperglycemic mothers. Glycemic control at 28 and 36 weeks, weight gain during pregnancy, pre-eclampsia, pregnancy-induced hypertension (PIH), mode of delivery, duration of exercise, emotional well-being, neonates’ birth weight, incidence of hypoglycemia, and NICU admission were compared among the study and control groups. The intervention group received an individualized NBMP from their diagnosis of hyperglycemia until delivery. RESULTS: The results showed a significant difference in blood glucose between the study periods and groups at p<0.05 as per repeated ANOVA. Also, diet scores had a significant influence on BMI and glycemic control at p<0.05. Logistic regression models, adjusted for potential confounders including baseline blood glucose, age, economic status, previous GDM, family history of DM as well as baseline BMI, diet score, physical activity, and maternal well-being score, indicated that the NBMP reduced the blood glucose and BMI significantly at p<0.05 in the study group. NBMP also reduced the risk of SGA/LGA and preterm/post-mature birth, as well as increased the exercise duration and emotional well-being of mothers. CONCLUSIONS: The study’s conclusions draw attention to the possible roles that maternal wellness, physical activity, and diet may have in reducing risks for both hyperglycemic mothers and their newborns. The NBMP resulted in higher adherence to lifestyle changes. Further research on a larger sample of hyperglycemic mothers is recommended to expand the generalizability of the findings.