As a major measure to promote government digital transformation, whether and how government data openness can have an impact on FDI inflows is a question worthy of in-depth study. Based on the panel data of 287 prefecture-level cities from 2009 to 2022, this paper takes the launch of the open government data platform as a quasi-natural experiment, and sets dummy variables according to the China Local Government Data Opening Report (Cities) released by DMG Digital and Mobile Governance Laboratory of Fudan University. A multi-point DID model is constructed to explore how government data opening becomes a new driving force to attract foreign investment. The results show that government data opening has a significant promoting effect on FDI inflows. After a series of robustness tests, the conclusion is still robust. Mechanism testing shows that government data opening, as an institutional innovation policy, can affect the regional business environment by improving government efficiency, promoting denationalization, promoting financial development, improving the legal environment, etc., thus promoting FDI inflow. Heterogeneity analysis shows that government data opening has a more significant promoting effect on FDI inflows in low-marketization regions, fourth-tier cities and below, inland cities, and central regions. In addition, by setting the replacement variables of core explanatory variables, it is found that the impact of government data opening on FDI inflows has a spillover effect on the neighboring regions of government data opening. In view of the above, it is suggested that the government should continue to deepen the data opening strategy, make full use of the promotion role of data opening to optimize the business environment, establish a linkage mechanism between data opening and FDI policy, attract high-quality FDI inflows, and guide FDI flows to low-marketization regions, inland cities, and fourth-tier cities and below, so as to promote the coordinated development of regional economy, strengthen the cooperation between neighboring areas of government data opening, and jointly enhance the competitiveness of the city.