Nordic listed firms in the industrial, energy, and consumer sectors are examined for the link between sustainability reporting and corporate financial performance during the changeover from the Non-Financial Reporting Directive (NFRD) to the Corporate Sustainability Reporting Directive (CSRD). ESG reporting is becoming a key tool for evaluating companies as sustainability becomes central to business strategy and investor decision-making. The CSRD is bringing in more consistent standards that will change how ESG information is generated and understood. The goal is to find out how well financial performance relates to sustainability reporting, determined by overall ESG scores and the E, S, and G components, and if CSRD has altered this connection. The study is based on signalling theory, stakeholder theory, and legitimacy theory, which describe how ESG disclosure can lower information asymmetry, build stakeholder trust, and impact financial results. Using panel data and regression analysis with control variables, a quantitative deductive approach is applied. The study is founded on a balanced panel of 114 Nordic listed companies, yielding 456 firm-year observations; listwise deletion yields a final usable sample of 413 observations. While ESG data comes from LSEG, financial performance is assessed using Return on Assets (ROA) and Return on Equity (ROE). To investigate the connections, Pearson correlation and several regression approaches are employed. The findings reveal a complicated picture. Although most of the ESG dimensions are not significant, Total ESG is negatively and significantly linked with ROA. For ROE, relationships are usually tenuous and minor. The absence of proof that CSRD has improved the link between ESG and performance implies that companies are still adjusting to the new reporting system. The study adds to ESG research by looking at how Nordic companies did during changes in rules and regulations. It shows that the link between ESG and financial performance is complicated and not always positive, and that any effects may take time to appear.