Financial constraints are one of the key factors that hamper the development of enterprises. Whether the settlement of well-known firm branches can alleviate corporate financial constraints remains to be explored. Based on the panel data of A-share listed companies in Shanghai and Shenzhen from 2007 to 2021, we treat the settlement of Big 4 branches as a quasi-natural experiment and constructs a multi-period DID model to investigate its impact on corporate financial constraints and the underlying mechanism. The results show that the presence of Big 4 branches significantly alleviates the financial constraints of firms in their cities. The mechanism test and further study found that Big 4 branches can alleviate corporate financial constraints by improving the local business environment and enhancing corporate transparency, and the effectiveness of the alleviation varies depending on the nature of the company and the level of internal and external governance. The conclusion of this study provides a reference for optimizing the regulatory policies of Big 4 and promoting the strategy of “becoming stronger and better” and brand building. Additionally, it provides insights into addressing enterprise financial challenges and enhancing the allocation of capital market resources for high-quality regional development.