Introduction: A Well-Baby Clinic (WBC) is a primary healthcare facility, where children are monitored for growth and development, receive routine immunization and their caregivers are given appropriate nutritional counselling. Objective: To assess the nutritional status (Underweight and anaemia) of under-5 children attending WBC of a Tertiary Care Institute of Kolkata and to identify any associated sociodemographic characteristics. Method: Across-sectional study was conducted for a period of 3 months (May 2023 to July 2023) among 106 under5 children, attending WBC of a Tertiary care Institute of Kolkata, selected using consecutive sampling. Face-to-face interviews were conducted among caregivers of children using an interview schedule, and anthropometric measurements and haemoglobin levels of the children were obtained using appropriate tools. Nutritional status was defined as Normal, Underweight, and Severely Underweight based on weight for age. Anaemia levels were categorized as mild, moderate, and severe based on haemoglobin levels. Association of sociodemographic characteristics with nutritional status was assessed using Binary Logistic Regression. Results:Among the children, 72.6% belonged within 12-24 months. Almost 19% and 17% of children were Moderately Underweight and Severely Underweight, respectively. Nearly 75% had a history of exclusive breastfeeding till 6 completed months of life, while 34% received formula feed. Regression analyses revealed statistically significant associations between the nutritional status of children with their gender and mothers' education. Conclusion: Nearly 36% of the under-5 children who attended the Well-Baby Clinic of a Tertiary Care Institute in Kolkata were categorised as Moderately or Severely Underweight, indicating that a sizable fraction of these infants had nutritional issues. Furthermore, the nutritional health of these children was found to be statistically significantly correlated with maternal education and gender, highlighting the significance of addressing sociodemographic inequities.