This study examines the impact of employee performance determinants on Small and Medium Enterprise (SME) firm performance by integrating multiple organizational factors into a unified analytical framework. Drawing on existing literature, key determinants such as leadership style, training and skill development, work motivation, work environment, technology adoption, employee engagement, organizational culture, compensation and incentives, and employee experience were identified as critical drivers of performance. The study adopts a quantitative, descriptive, and causal research design, collecting primary data from 196 SME respondents in Kolkata using a structured questionnaire. Statistical analysis was conducted using SPSS, employing descriptive statistics, correlation, and multiple regression techniques. The findings reveal that the proposed model explains 72.2% of the variance in SME firm performance (R² = 0.722), indicating strong explanatory power. Among the determinants, training and skill development emerged as the most significant predictor, followed by work environment and organizational culture. In contrast, variables such as leadership style, motivation, technology adoption, and employee engagement showed no direct significant impact in the regression model. The study concludes that human capital development and supportive organizational conditions are the most influential drivers of SME performance. The findings provide valuable insights for policymakers and managers to prioritize training, workplace improvement, and cultural development to achieve sustainable growth and competitiveness in SMEs.