AI systems fail not because of model limitations but because of ungoverned data. This article presents a comprehensive strategic and architectural framework for enterprise AI data governance, covering the full data lifecycle from ingestion through feedback, the organizational design of data ownership and accountability, the role of data contracts in scaling AI across teams, guardrail architecture for production inference safety, and the executive metrics that signal platform health. The central argument is that data governance is not a compliance activity but a platform infrastructure investment that compounds competitive advantage over time. Organizations that build disciplined data ecosystems will not simply deploy better AI — they will continuously improve it in ways that are difficult to replicate.