This research investigates the impact of Sustainability Reporting on Firms' Financial Performance: Special Reference to the Listed Companies in the Colombo Stock Exchange in Sri Lanka. The study evaluates the impact of economic, environmental, and social disclosures as the sustainability reporting on the firm's financial performance, including Listed Companies in Sri Lanka. It was able to identify the level of disclosures on sustainability performance is lower than the expectation and compare foreign listed entities. As the sustainability disclosure is not a mandatory part to be provided in annual reports and voluntarily disclosing the performances are very low. Thus, 102 listed companies with Sustainability reporting of selected for the analysis purpose from 138 listed companies. All these companies follow the Global Reporting Initiative (GRI) G4 guidelines. This study considers secondary data collected from the annual reports, both from the Financial and Non-Financial reporting. The descriptive analysis, correlation tests, and regression analysis have conducted for analyzing purposes. The findings show a moderate positive relationship between the sustainability reporting, including economic, environmental, and social disclosures and ROA on financial performance. Thus, the consideration either on sustainability performance or on financial performance a company can achieve a moderate positive vibe of the year.