The manufacturing sector’s adherence to managing natural resources from the environment still needs to be improved. This study’s objective is to determine how Corporate Social Responsibility (CSR) influences the financial performance of manufacturing firms featured in the LQ45 Index, as measured by Return on Assets (ROA), Return on Equity (ROE), and Net Profit Margin (NPM). All manufacturing companies that are included in the LQ45 Index’s population for this study were sampled using the purposive sampling method. This study uses secondary data from the CSRI based on the Global Reporting Initiative (GRI) G4 standard for 2018–2020 and the annual reports of companies in the manufacturing industry sector listed on the LQ45 Index. Moreover, applying a quantitative methodology, descriptive statistical methods, conventional assumption tests, and simple linear regression analysis were applied in this study’s data analysis. The results of the study proved that CSR has a significant effect on ROA but does not affect the ROE and NPM of LQ45 manufacturing companies. In accordance with the signaling theory, CSR disclosure sends a favourable message to outsiders, which stakeholders and shareholders will respond to through changes in business earnings. CSR implementation can establish a positive image for the company, but it can also improve the company’s image in both the commodity and capital markets. Investors will be more attracted to a company with a positive corporate image since a positive corporate image increases consumer loyalty. As consumer loyalty rises, the company’s sales will likewise rise, and its profitability will increase as a result. This paper opens a new research path in corporate social responsibility and financial performance for possible links among variables; a matter that has not been previously explored in Indonesia Manufacturing Public Companies.