A systematic literature review of assurance and greenwashing in sustainability reporting

This study synthesizes empirical findings on the impact of sustainability assurance on greenwashing through a systematic review of 41 peer-reviewed articles indexed in Scopus and Web of Science up to March 2025, following PRISMA 2020 and Mixed Methods Appraisal Tool protocols. The analysis uncovers a dual-edged assurance phenomenon: robust assurance scope, level, and provider quality reduce greenwashing, while weak or symbolic implementation enables assurance-washing. Key adoption drivers include external pressures and internal motivations, with underassurance stemming from capacity limitations and assurance-washing from strategic legitimacy pursuits. Effective mitigation of greenwashing is more likely when implementation is coordinated across regulations, verification mechanisms, internal governance, and technological tools. Evidence primarily draws on developed economies and quantitative methodologies. Drawing on institutional (including neo-institutional), legitimacy, and stakeholder theories, this research delineates conditions under which sustainability assurance operates as genuine governance rather than ceremonial legitimation.