The survival and development of enterprises cannot be separated from the simultaneous excellence in exploitative and exploratory innovations, i.e., ambidextrous innovation. Despite enhanced intelligent decision-making and rapid response, the impact of digital transformation on ambidextrous innovation in Chinese high-speed rail industry remains unexplored. Based on the data of 108 listed companies in Chinese high-speed rail industry from 2009 to 2021, this study empirically evaluates the impact of digital transformation on exploitative and exploratory innovations. The empirical results indicate that digital transformation can significantly promote the exploitative and exploratory innovations of the high-speed railway industry in China. According to the results of mechanism analysis, it can be concluded that digital transformation energizes these innovations by enhancing both internal knowledge recombination and external knowledge acquisition. Meanwhile, digital knowledge of Top Management Team (TMT) specifically strengthens the positive impacts. In addition, results from the heterogeneity analysis imply that digital transformation significantly enhances the ambidextrous innovation among enterprises in the eastern region, while it does not significantly affect those in the central and western regions. This study also confirms a significantly positive correlation between digital transformation and ambidextrous innovation of old enterprises; however, this relationship is not significant for young enterprises.