Abstarct: This study aimed to investigate the impact of Diffusion of Innovation theory and financial behavior on the continuance intention of using digital financial services and fintech applications, with the mediating role of psychological comfort, among users in Iran. The research is applied in purpose and employs a descxriptive-survey methodology. The statistical population comprised urban middle-class individuals who use digital financial services and fintech applications, particularly in the four major cities of Tehran, Mashhad, Isfahan, and Shiraz. Using simple random sampling, a total of 384 participants were selected. Data were collected through a standardized questionnaire, whose validity and reliability were confirmed. The results of hypothesis testing indicated that relative advantage, perceived compatibility, trialability, perceived trust, cognitive involvement, perceived usability, and psychological comfort have a significant positive effect on psychological comfort. Moreover, a significant positive relationship between psychological comfort and continuance intention was also confirmed. These findings are consistent with prior research emphasizing the importance of Diffusion of Innovation theory and financial behavior theory in promoting psychological comfort. This study suggests that future research could test the proposed model across different social laxyers and contexts, examine the mediating role of additional variables, and conduct longitudinal studies to assess the sustainability of the observed effects over time, providing valuable directions for further investigation.