As global brands operate across multi-channel digital ecosystems—social platforms, mobile apps, retail systems, CRM databases, ad networks, and cloud environments—data fragmentation has emerged as a critical strategic challenge. Cross-platform data integration enables brands to unify consumer profiles, streamline analytics, improve customer experience, enhance personalization, and facilitate real-time decision-making. This paper synthesizes literature from enterprise data architecture, marketing analytics, interoperability standards, cloud computing, and identity resolution. It introduces the Global Cross-Platform Data Integration Framework (G-CDIF) comprising five layers: Data Collection & Ingestion, Identity Resolution, Interoperability & Standardization, Real-Time Orchestration, and Governance & Compliance. The study emphasizes the importance of privacy regulations, API infrastructure, and cultural data variability for multinational firms operating across borders.