The purpose of this study is to examine the impact of FinTech adoption on the non-financial performance of private banks, with an emphasis on the mediating role of circular economy principles. In this study, non-financial performance comprises three dimensions: customer satisfaction, internal processes, and organizational learning and growth. This research is applied in terms of purpose and descriptive–survey in terms of methodology. The statistical population includes managers and employees of private banks in the cities of Tehran and Karaj. Using Cochran’s formula for an unlimited population, a sample size of 385 respondents was determined and selected through convenience sampling. Data were collected using a standardized questionnaire, and SPSS and PLS software were employed to analyze the data through PLS-SEM. The findings indicate that FinTech adoption has a positive and significant effect on all three dimensions of non-financial performance. Moreover, circular economy principles have a positive and significant impact on the non-financial performance of banks and play a significant mediating role in the relationship between FinTech adoption and non-financial performance. Overall, the results suggest that FinTech, by facilitating the implementation of circular economy strategies, can enhance operational efficiency, improve internal processes, and increase customer satisfaction in private banks.