The reform of the IPO registration system is a crucial step toward the maturity, improvement, and marketization of the securities market. In recent years, the trend of corporate financialization has become increasingly evident. Based on data from firms listed on the ChiNext Market and the Main Board, this paper constructs a Propensity Score Matching-Difference-in-Differences (PSM-DID) model and an RDD-DID model to examine the impact of IPO registration system reform on corporate financialization and analyze its underlying mechanisms from multiple perspectives. The estimation results of both models indicate that the IPO registration system reform has significantly increased firms’ financialization levels. Furthermore, a series of robustness checks confirm the reliability of the findings. The mechanism analysis reveals that the reform has promoted corporate financialization by lowering listing thresholds, alleviating financing constraints, and intensifying market competition. Meanwhile, its information disclosure mechanism has to some extent curbed financialization. Further heterogeneity analysis shows that the reform’s promoting effect is more pronounced in non-state-owned enterprises, firms with lower growth potential, and those with weaker corporate social responsibility (CSR) performance. This study enriches the literature on the policy impact of IPO registration system reform, provides a new perspective on how such reforms influence corporate financialization, and offers important implications for curbing excessive financialization in real-sector enterprises, deepening IPO registration system reform, and further improving capital markets.