External Auditor Attributes and Sustainability Reporting: Evidence from Nigerian Banking Sector

In recent years, the growing global concern about environmental, social, and governance (ESG) issues has intensified the demand for credible and transparent sustainability reporting, yet the reliability of such disclosures remains a persistent challenge, especially in developing economies. This study investigates the effect of external auditors’ attributes on sustainability reporting among listed deposit money banks in Nigeria over the period 2015–2024. Using an ex post facto research design and Ordinary Least Squares (OLS) regression analysis, the study examines how audit firm size, auditor tenure, and audit fees influence the quality and extent of sustainability disclosures. Data were obtained from the annual and sustainability reports of thirteen listed banks. The results show that audit firm size, auditor tenure, and audit fees each have positive and significant effects on sustainability reporting, indicating that audit quality enhances disclosure credibility. The study concludes that strengthening audit quality can improve sustainability transparency and stakeholder confidence in Nigeria’s banking sector.