Though their activities, companies have an impact on environmental problems and nature conservation. The accounting sector can play a role in environmental conservation efforts related to environmental costs, and the implemention of the Corporate Sustainability Management System (CSMS) could be a key factor that can improve the company’s financial performance. This study aims to determine how green accounting through the application of CSMS can improve the financial performance of manufacturing companies in Indonesia, a developing country. The sampling method used was purposive sampling, while the research sample consisted of 38 companies that had followed PROPER and were indexed on the IDX. Data were analyzed using the Structural Equation Modeling (SEM) method known as the Partial Least Square (PLS) method. The results of this study indicate that manufacturing companies in Indonesia are able to implement green accounting by allocating appropriate environmental costs by earmarking a portion to carry CSMS implementation so as to improve financial performance. People in Indonesia consider that manufacturing companies that have good company rankings in the evaluation program for company performance ratings in environmental management run by the Indonesian Ministry of Environment are in a position to generate customer loyalty, especially in financial performance.