This study investigates the impact of FinTech adoption on corporate green investment, offering new insights into the broader consequences of digital financial transformation. Using a panel dataset spanning from 2007 to 2022, we find that FinTech adoption significantly reduces green investment, particularly among non-state-owned enterprises (non-SOEs), firms with low agency problems, low labor intensity, and those operating in highly marketized regions. Mechanism analysis suggests that expanded financing channels enabled by FinTech lead firms to prioritize low-risk, short-term investments, thereby reducing their propensity to engage in long-term, uncertain green projects. These findings suggest that FinTech is unlikely to inherently promote sustainable business practices in its current form. The study offers practical implications for policymakers, FinTech developers, and corporate managers, highlighting the need to incorporate broader sustainability considerations into the design of financial algorithms when navigating the intersection of digital finance and environmental strategy.