In recent decades, corporate reporting systems have undergone a fundamental paradigmatic shift, where a sole focus on financial data no longer meets the growing needs of stakeholders. Global concerns about climate change, social justice, ethical governance, and corporate long-term sustainability have led organizations to expand their reporting beyond traditional financial statements to include disclosures of Environmental, Social, and Governance (ESG) information.
This evolution has direct consequences for the auditing profession. Auditors, whose primary duty was historically to "express an opinion on financial statements," now face new expectations. They must also evaluate and provide assurance on non-financial data, sustainability metrics, climate risks, ethical risks, and governance structures. This expansion in scope has transformed the nature of auditors' professional judgment from a quantitative-financial activity into a multidimensional, interdisciplinary process based on the analysis of emerging risks.
On the other hand, the introduction of new standards such as IFRS S1, IFRS S2, the EU's ESRS, and frameworks like GRI and SASB has turned non-financial reporting into an institutional and regulatory requirement. These changes have made it inevitable to review auditing methodologies, evidence-gathering tools, internal control evaluations, and risk analysis. A review of literature from 2018 to 2025 indicates that sustainability reporting can enhance audit quality directly or indirectly by reducing information asymmetry, increasing transparency and managerial accountability, improving non-financial internal controls, and reducing earnings management incentives.

However, recent literature warns that poor-quality ESG reporting and the phenomenon of "greenwashing" can introduce ambiguity into auditor judgment and potentially even reduce audit quality. Therefore, a key gap in the literature remains: it is still not entirely clear through which causal pathways and mechanisms non-financial and sustainability reporting affect the new role of the auditor, professional judgment, and audit quality. This issue is particularly significant in developing countries, which face challenges such as weak oversight, a lack of standardized data, and low disclosure maturity.
The aim of this review article is to provide a systematic analysis of the new literature and explain the research question: How do non-financial and sustainability reporting become drivers for transforming the role of auditors, and through which pathways do they affect professional judgment and audit quality?