Digital micro-targeting refers to the use of granular consumer data—behavioural traces, psychographic profiles, geolocation patterns, and algorithmic predictions—to tailor marketing content to highly specific audience segments. While widely practiced within national markets, cross-border micro-targeting is increasingly shaping international commerce, political influence, cultural messaging, and global brand expansion. This study analyzes the mechanisms, cross-country variations, ethical constraints, data protection laws, and platform governance structures influencing global micro-targeting. Using hypothetical datasets and comparative analysis across regions, findings reveal that micro-targeting effectiveness is mediated by cultural norms, regulatory frameworks, platform algorithms, and digital infrastructure maturity. A multi-layer global micro-targeting strategy model is proposed to balance performance and compliance.