This thesis investigates how Big Tech corporations discursively construct authority in the governance of Artificial Intelligence (AI), and what this reveals about the shifting boundaries between corporate and state-led regulation. As AI technologies become increasingly embedded in everyday life, the question of who governs them has moved to the centre of international policy debates. Drawing on neoliberalism as the theoretical framework, the study conducts a discourse analysis of policy documents, ethical frameworks, and public statements from Google and Microsoft. The findings show that both corporations frame themselves as legitimate governors rather than as subjects of regulation. They manage this by using the language of ethics, responsibility, and technical expertise to justify their roles. Through internal frameworks, voluntary standards, and strategic partnerships, they construct a model of governance that is decentralised, privatised, and detached from legal enforcement. This thesis argues that corporate governance remains conditional on the legal and institutional structures of the state. What is shifting is the way authority is claimed and made intelligible through discourse. These findings contribute to broader debates in international relations about legitimacy, authority and neoliberal restructuring of global governance.