Background: Childhood obesity is a growing public health concern, particularly in urban areas like Cuttack City, Odisha, where changing lifestyles and dietary habits have contributed to an increasing prevalence of obesity among primary school students. Maternal influence plays a critical role in shaping children's eating behaviours and physical activity levels. This study aimed to evaluate the effectiveness of nutritional education provided to mothers of obese primary school students in reducing their children's Body Mass Index (BMI) over a 6-month follow-up period. Materials and Methods: A quasi-experimental study was conducted in a primary school in Cuttack City. A total of 100 obese students (BMI ≥ 95th percentile for age and sex) and their mothers were enrolled and divided into two groups: the intervention group (n=50) and the control group (n=50). Mothers in the intervention group attended six structured nutritional education sessions over onemonth, focusing on balanced diets, portion control, healthy snacking, and the importance of physical activity. Anthropometric measurements (height, weight, and BMI) were taken at baseline and after 6 months. Data were analyzed using SPSS software version 17, with paired t-tests for within-group comparisons and independent t-tests for between-group comparisons. A p-value of <0.05 was considered statistically significant. Results: The mean BMI of students in the intervention group decreased significantly from 23.4 ± 1.2 at baseline to 21.8 ± 1.1 at 6 months (p < 0.05). In contrast, the control group showed a slight increase in mean BMI from 23.6 ± 1.3 to 23.9 ± 1.4 (p > 0.05). The reduction in BMI in the intervention group was significantly greater than in the control group (p < 0.05). Additionally, mothers in the intervention group reported improved knowledge and practices related to healthy eating and physical activity. Dietary habits also improved, with increased consumption of fruits and vegetables and reduced intake of junk food and sugar-sweetened beverages. Conclusion: This study demonstrates that nutritional education for mothers is an effective strategy for reducing BMI among obese primary school students. The findings align with previous research highlighting the importance of parental involvement in managing childhood obesity. By empowering mothers with knowledge and practical skills, the intervention addressed the root causes of poor dietary habits and sedentary behaviours. The results underscore the potential of school-based programs that involve parents in promoting healthy lifestyles. However, the study's limitations, including single school and short follow-up period, suggest the need for involving more schools , longer-term studies to confirm these findings. Policymakers and educators should consider integrating maternal nutritional education into school health initiatives to combat the growing burden of childhood obesity.