This study examined the effect of organizational culture on employee performance at Buna International Bank's Bahir Dar City branches, guided by the Competing Values Framework (CVF), which includes clan, adhocracy, market, and hierarchy cultures. The study aimed to explore how these four cultural dimensions influence employee job performance in a private banking context. A quantitative research approach was used, employing both descriptive and explanatory research designs. Data were collected through a structured, self-administered questionnaire adapted from Cameron and Quinn’s (1990) OCAI model and Koopmans et al. (2014), distributed to all 208 professional employees across 17 branches, with 200 valid responses analyzed. Descriptive statistics, Pearson correlation, and multiple linear regression analyses were conducted using SPSS. The results showed that all four cultural types were present, with hierarchy culture being the most strongly perceived. Regression analysis also revealed that hierarchy culture had the most substantial positive effect on employee performance (β = 0.619, p < 0.001), followed by clan (β = 0.290), adhocracy (β = 0.182), and market culture (β = 0.136). The model explained 82.7% (adjusted R² = 0.827) of the variance in employee performance, indicating strong explanatory power. The study concludes that organizational culture significantly influences employee performance, especially through structured (hierarchical) and people-focused (clan) cultures. It is recommended that Buna Bank strengthen its formal systems and teamwork values, while encouraging innovation and performance orientation. Future studies are encouraged to expand across regions, integrate qualitative methods, or include mediating variables such as leadership style and job satisfaction for deeper insight.