Corporate sustainability reporting is currently a prominent issue in the global business world, with companies worldwide actively publishing sustainability reports to meet the demands of different stakeholders regarding social, environmental, economic, and governance concerns. The existing literature has proved that companies that participate aggressively in corporate sustainability reporting tend to have higher firm value, experience tremendous growth rates in terms of size and profitability, have a high capital and asset base, are lowly geared, and gain a competitive edge in the industry in which they operate. The study examines the link between corporate sustainability reporting and the financial performance of firms listed at the Nairobi Securities Exchange. Corporate governance, social, environmental, and economic pillars were used as indicators of corporate sustainability reporting. The Global Reporting Initiative framework will be employed to establish the corporate sustainability reporting scores and construct the sustainability reporting index. Financial performance was measured by return on assets. The study is anchored on the stakeholder theory supported by legitimacy and the tripled bottom-line theories. The target population comprises sixty-seven companies listed in Kenya. Secondary data was collected from the company integrated reports, published accounts, and the accounts filed with the Nairobi Securities Exchange for the period 2011 to 2020. The study adopted a cross-sectional correlational research design. Descriptive statistical tests carried out include mean, standard deviation, kurtosis and skewness. Correlation analysis was done to test and establish the direction of the relationship between the study variables. Regression analysis was employed to test the hypotheses of the study. Generally, the study findings are that corporate sustainability reporting had a significant positive effect on financial performance. The empirical results of this study showed that corporate sustainability reporting led to improved financial performance among listed companies, although sustainability reporting in Kenya was purely voluntary. Therefore, Kenya’s Capital Markets Authority should consider making corporate sustainability reporting compulsory for all listed companies. Further research can be extended to include non-listed companies and the application of other sustainability reporting frameworks. Keywords: Corporate Sustainability Reporting, Financial Performance, Global Reporting Initiative, Nairobi Securities Exchange.