["Business Ethics, the Environment &Responsibility, EarlyView. ", "\nABSTRACT\nCurrently, corporate sustainability is primarily assessed through companies' own sustainability reports and evaluations conducted by NGOs and rating agencies. These approaches present several limitations, including potential reporting bias and limited transparency in evaluation methodologies. In response, this paper proposes CSR‐IRIS‐v2, a big data and sentiment analysis method designed to measure public sentiment regarding corporate sustainability as expressed on social media platforms. Rather than assessing sustainability performance directly, CSR‐IRIS‐v2 captures how social media users discuss and perceive corporate sustainability issues online. The method introduces a new lexicon based on the European Sustainability Reporting Standards (ESRS) under the Corporate Sustainability Reporting Directive (CSRD) and replaces previous programming‐intensive procedures with Microsoft Azure Machine Learning (Azure ML), thereby enhancing usability and accessibility. The approach enables the assessment of the salience of corporate sustainability topics in social media discourse, the relative attention devoted to different sustainability dimensions, and the polarity of expressed sentiment (positive, neutral, or negative) toward these dimensions. The method is illustrated through its application to 10 companies operating in Spain. The findings provide insights into public perception of corporate sustainability and may support companies, stakeholders, and evaluators in understanding reputational dynamics and perceived corporate sustainability.\n"]