This study examines the impact of CEOs' financial backgrounds on the financialization of firms, with a particular focus on the mediating roles of managerial overconfidence and financing constraints. Drawing on data from 2013 to 2022 and analyzing 1,475 firm-year observations of non-financial firms listed on the Tehran Stock Exchange, the study employs panel data regression to test the proposed relationships. The results indicate that CEOs with financial experience tend to promote the accumulation of financial assets within firms, potentially due to their familiarity with financial markets and perceived ability to manage such investments. The findings also highlight two mediating mechanisms: overconfident CEOs, influenced by psychological biases, are more inclined toward financial investments; and firms with greater financing constraints are more likely to adopt financialization as a response to capital limitations. Moreover, sub-sample analysis shows that the relationship between a CEO’s financial background and corporate financialization is stronger in larger firms with lower levels of internal cash flow. This suggests that firm-specific characteristics, such as size and liquidity, shape the intensity of this association. The findings support the agency theory and the resource-based view, which emphasize the role of managerial discretion and unique capabilities in shaping strategic financial decisions. This research contributes to the literature by clarifying how executive traits and contextual factors interact to drive financialization. It also offers practical insights for corporate governance, particularly in selecting executives and designing oversight mechanisms that align managerial behavior with long-term value creation.