The proliferation of illegal cosmetics containing prohibited substances on e commerce platforms in Indonesia poses significant risks to consumer protection. This study examines the issue under the framework of Law Number 8 of 1999 on Consumer Protection (UUPK), analyzing its application to safeguard consumers. Employing a normative-empirical approach, the research highlights how inadequate regulations and insufficient oversight have allowed unsafe products to circulate freely, endangering public health. The findings emphasize the role of the Food and Drug Supervisory Agency (BPOM) in monitoring and enforcing compliance but also reveal existing challenges, including limited resources and consumer awareness. Cases involving hazardous ingredients, such as mercury and hydroquinone, are discussed to illustrate the severe health implications of using such products. The study concludes that more robust regulatory measures, stricter enforcement, and comprehensive consumer education are essential to curb the circulation of illegal cosmetics and ensure compliance with the UUPK. Enhanced e-commerce accountability and government collaboration are also recommended to protect consumer rights and promote safer marketplace practices.