Sustainability reporting and assurance have rapidly shifted from a largely voluntary corporate practice to a standard-setting, regulatory, and investor-relevant domain. This transition elevates the ethical stakes for accountants: sustainability information is increasingly used in capital allocation, risk pricing, and stakeholder accountability, creating new incentives for misrepresentation, selective disclosure, and “ethical fading.” Accounting education therefore must evolve from treating sustainability as an elective topic toward embedding sustainability ethics as a core professional competence—covering integrity, objectivity, due care, skepticism, evidence, governance, and independence across sustainability reporting and assurance engagements. This conceptual research article synthesizes interdisciplinary ethics scholarship and accounting education research to propose an integrated Sustainability Ethics Competency Model (SECM) and a curriculum architecture aligned with emerging global standards and expectations. The article draws on developments including IFRS Sustainability Disclosure Standards (IFRS S1 and IFRS S2, effective for annual reporting periods beginning on or after 1 January 2024) (IFRS), the International Ethics Standards Board for Accountants’ (IESBA) sustainability assurance ethics standards and related revisions (with stated effective dates from December 2026 and certain provisions from July 2028) (Ethics Board), and IFAC’s embedding of sustainability within International Education Standards revisions (announced March 2025) (IFAC). A pedagogical roadmap is presented using case-based learning, moral reasoning exercises, assurance simulations, and assessment rubrics that evaluate ethical judgment under sustainability-specific dilemmas (e.g., double materiality tensions, value-chain evidence limits, and governance pressures). The paper concludes with implementation guidance for faculty, accreditation implications, and a future research agenda.