Workforce diversity has become a central organisational concern in large service institutions, yet limited empirical evidence exists on how it influences employee performance within Ethiopian regional operational settings, particularly in the telecommunications sector. This study was therefore conducted to examine the effect of four workforce diversity dimensions gender, age, educational, and work experience diversity on employee performance, guided by the Resource-Based View, Social Identity Theory, Information and Decision-Making Theory, and Inclusion Theory. The study was carried out in the North West Region of Ethio Telecom, Bahir Dar, Ethiopia. A quantitative, non-experimental descriptive correlational design was adopted, using a cross-sectional survey questionnaire to collect data from a proportionally stratified random sample of 250 permanent employees drawn from regional shops and the regional office, out of a population of 660. Collected data were analysed using SPSS Statistics, applying descriptive statistics, Cronbach's alpha reliability testing, Pearson's correlation, and multiple linear regression analysis. Findings revealed statistically significant positive relationships between all four diversity dimensions and employee performance, with educational diversity showing the strongest effect (β = .329, p < .001, M = 3.85, SD = 0.50), followed by work experience diversity (β = .302, p < .001, M = 3.76, SD = 0.52), age diversity (β = .261, p < .001, M = 3.74, SD = 0.48), and gender diversity (β = .187, p = .001, M = 3.73, SD = 0.50); the model explained 71.2% of the variance in employee performance (R² = .712). Employee performance registered a moderately high mean (M = 3.40, SD = 0.63), the highest dispersion among all variables, indicating greater variability in performance perceptions. The study concludes that inclusive management of workforce diversity meaningfully strengthens employee performance, and recommends targeted diversity recruitment, structured cross-generational mentoring, and inclusive leadership development to fully leverage these benefits, while calling for further research extending this analysis to other regions and sectors.