Introduction Compulsive buying disorder (CBD), also referred to as compulsive buying-shopping disorder, shopping addiction, oniomania, or pathological buying, is characterized by excessive and poorly controlled preoccupations, urges, or behaviors related to shopping and spending. Digitalization in e-commerce and payment systems has made indulgence in shopping easier than ever. CBD is a growing concern, especially in the younger generation. Aim To determine the prevalence of CBD and its associated factors among undergraduate medical students. Methodology A cross-sectional study was done among undergraduate medical students in a tertiary college in Chengalpattu district, Tamil Nadu, India. A total of 300 students participated in the study. A pretested semi-structured questionnaire was used to collect socio-demographic details and information on factors associated with CBD. A validated scale was used to assess CBD. Data analysis was done using IBM SPSS Statistics for Windows, Version 25 (IBM Corp., Armonk, NY). Results The prevalence of CBD was found to be 68/300 (22.6%) among the undergraduate medical students. A total of 26/103 (25.2%) males were affected compared to 42/197 (21.3%) female students. Being tempted to buy during deals and offers, social media influence, and not having a habit of saving money were found to be significantly associated with CBD. Conclusion CBD is an often-overlooked behavioral concern in academic settings, and its presence is highlighted in this study. These findings underscore the influence of social media, peers, and strategic deals by e-commerce services on students' purchasing habits. Interventions to identify and treat CBD in the early stages are important to prevent long-term financial and psychological consequences.