The study investigates the effect of bank fintech on the bank efficiency in Vietnam, an emerging country in Southeast Asia. Bank fintech variables are formulated using bank intangible assets, based on existing publications regarding fintech and the utilization of emerging technologies by commercial banks. In addition, the bank efficiency variable is calculated using the Data Envelopment Analysis approach. Our hypothesis suggests a positive effect, which aligns with previous studies. To collect the data, information was obtained from the annual reports, where banks disclosed their implementation of emerging technologies to enhance performance. The panel data of 23 banks from 2011 to 2020 were compiled from various sources, including Vietstock (annual reports and financial statements) and the World Bank (macroeconomic indicators). To test our hypothesis, the authors employed multiple approaches, including fixed-effect (FE), Random-effect (RE), Feasible Generalized Least Square (GLS), and Tobit approaches. The estimation results are mixed, with most suggesting a negative effect of bank fintech on the bank efficiency. This indicates that bank investments in technology innovation does not always yield effective results. These findings support the productivity paradox hypothesis, suggesting that an increase in technology innovation investment may decrease productivity. This study makes a significant contribution to the existing literature on the relationship between bank fintech and bank efficiency. Moreover, it provides evidence that bank investments in technology innovation may be ineffective for commercial banks in Vietnam.