In an environment where vendors face dozens of security questionnaires across frameworks such as [SOC 2](https://secureframe.com/hub/soc-2/what-is-soc-2), [ISO 27001](https://www.iso.org/standard/27001), GDPR and CCPA, generating precise, context‑aware evidence quickly is a major bottleneck. This article introduces an ontology‑guided generative AI architecture that transforms policy documents, control artifacts and incident logs into tailored evidence snippets for each regulatory question. By coupling a domain‑specific knowledge graph with prompt‑engineered large language models, security teams achieve real‑time, auditable responses while maintaining compliance integrity and reducing turnaround time dramatically.