Viral marketing emerges as a potent strategy for driving consumer buying behaviour in cosmetics, urging companies to prioritise innovative Reels and user-generated content on social platforms for sustained market growth. This study examines the influence of viral marketing on purchase intentions for cosmetic products among urban consumers in Bangalore, India. Employing a descriptive survey research design, primary data were collected via structured questionnaires from 80 randomly selected respondents using random sampling from Basaveshwar Nagar. The study recommends that cosmetic brands collaborate with micro-influencers, develop AR-enhanced short videos, monitor engagement metrics via A/B testing, and target young urban women to boost conversions and ROI organically.