<p>This Perspective paper argues that generative artificial intelligence (AI) is transforming the foundations of academic integrity in higher education, not by encouraging individual misconduct but by exposing systemic weaknesses in policy design, assessment practices, and institutional culture. Drawing on sociocultural and cognitive theories, the paper introduces the Higher Education Integrity Ecosystem Model, a conceptual framework that explains integrity as an emergent property of four interacting layers: governance and policy, assessment design, institutional and cultural norms, and individual moral agency. Unlike existing models that emphasize individual responsibility or organizational compliance, this perspective positions AI as a transformative force that reshapes authorship, authenticity, and ethical decision-making across all layers of the system. The paper argues that sustaining integrity in the Age of AI requires systemic redesign rather than incremental adjustments. Key implications for practice include developing transparent, process-oriented AI-use policies; redesigning assessments to emphasize human judgment and learning processes; cultivating institutional cultures that normalize disclosure and responsible AI use; and supporting students in exercising moral agency when interacting with increasingly capable AI tools. By aligning integrity governance with the realities of ubiquitous AI, the model offers a pathway toward ethical sustainability that reinforces fairness, trust, and human agency. The paper also highlights connections to the United Nations Sustainable Development Goals, particularly Quality Education (SDG 4) and strong, just institutions (SDG 16).</p>