The study examines the effect of managers’ personality traits on employee job performance in the telecommunication industry in Ghana. A cross-sectional survey design was adopted using structured questionnaires to collect primary data from a sample of 350 employees and managers in four selected telecommunication firms. Correlation and regression techniques are used. The study discovered that the dominant personality trait of leaders’ in the telecommunication industry in Ghana is open-minded with extraversion. Furthermore, there is a fairly strong significant positive relationship between each of the five leaders’ personality traits and employee job performance. After controlling for demographic characteristics, it was revealed from the analysis that the personality traits of leaders have significant effects on employee job performance. Years of experience and age collectively were very significant to job performance. The study recommends among other things that formalized leadership training programs should be instituted in the telecommunication industry in Ghana to train leaders and employees on leaders’ personality traits and its effect on employee performance.