Breastfeeding is widely recognized as one of the most effective public health practices for ensuring optimal child growth, development, and nutritional well-being. Maternal attitude toward breastfeeding plays an important role in determining infant feeding behaviour and influencing nutritional outcomes during early childhood. The present study was conducted to assess mothers’ attitudes toward breastfeeding and to evaluate the nutritional status of children in Nathnagar Block, Bhagalpur District, Bihar. A descriptive and analytical cross-sectional research design was adopted. The study included a sample of 120 mothers and their children aged 0–5 years selected through simple random sampling. Primary data were collected using a structured interview schedule, while anthropometric measurements were used to assess nutritional status according to WHO Child Growth Standards. Descriptive and inferential statistical techniques including frequency, percentage, Chi-square test, and Pearson correlation analysis were applied. The findings revealed that 60.0% of mothers demonstrated a positive attitude toward breastfeeding, while 71.6% supported early initiation of breastfeeding and 66.7% supported exclusive breastfeeding for the first six months. Nutritional assessment showed that 38.3% of children were underweight, 41.7% experienced stunting, and 31.7% exhibited wasting. Inferential analysis demonstrated a significant association between mothers’ attitudes and breastfeeding practices (χ² = 12.48, p < 0.05) and a significant relationship between breastfeeding practices and nutritional status (χ² = 14.62, p < 0.05). A moderate positive correlation was also observed between maternal attitude and child nutritional status (r = 0.46, p < 0.05). The study concludes that improving maternal awareness, strengthening breastfeeding counselling, and enhancing community-based nutrition interventions may contribute to improved child nutritional outcomes and reduction of childhood undernutrition in the study area.