E-commerce sites and marketers need to personalize customer experiences without breaking the law because people are becoming more worried about data privacy and third-party cookies are being phased out. This paper shows how to use machine learning to create a framework for customer segmentation and media optimization that protects privacy. The system is made to work in decentralized, privacy-sensitive settings. It uses unsupervised clustering, predictive modeling, and real-time decisioning engines to give users useful information without giving away their identity. Our method uses federated learning and cleanroom technologies to make sure that it follows laws like GDPR and CCPA. This is different from traditional commercial segmentation tools that rely heavily on centralized data collection and unclear personalization methods. The framework shows big improvements in performance when tested on real-world e-commerce datasets. It gets a 23% increase in Return on Ad Spend (ROAS), a 17% increase in conversion rates, and a 14% drop in cost-per-acquisition. The proposed solution is a scalable and compliant replacement for old marketing tools. It lets you target people more accurately and buy media more efficiently in today's changing digital world.

Customer Segmentation, Privacy-Preserving Analytics, Federated Learning, Digital Advertising, Machine Learning, Media Optimization, Data Cleanrooms, E-commerce Personalization

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