Based on data from listed companies in China's Shanghai and Shenzhen A-shares from 2016 to 2020, this study empirically investigates the impact of digital finance on corporate innovation efficiency and its underlying mechanisms using fixed effects models and mediation effect models. The results indicate that digital finance can enhance corporate innovation efficiency, which remains robust after sensitivity tests. Mediation analysis reveals that digital finance promotes innovation efficiency by alleviating financing constraints and financial distress. Heterogeneity tests show that the positive impact of digital finance on innovation efficiency is more pronounced in non-state-owned enterprises, small and medium-sized enterprises, companies located in central and western regions, non-first-tier cities, areas with lower levels of marketization. This research provides valuable policy insights for advancing the adoption of digital financial technologies and enhancing corporate innovation efficiency.