The purpose of this study was to find out how principals’ leadership styles affect teachers’ job performance in public secondary schools in Kieni West Sub County. Descriptive survey research design was adopted. This study targeted all the 22 principals and 262 teachers serving in public secondary schools in Kieni West Sub County, Nyeri County. Stratified random sampling was employed to select 8 principals and 74 teachers to participate in the study. The researcher used principals and teachers’ questionnaires to collect the needed data. Data was analyzed using both quantitative and qualitative procedures. Chi-square tests were conducted to establish the relationship between principals’ leadership style and teachers’ job performance while correlation tests were employed to establish the magnitude and direction of the relationship between principals’ leadership styles and teachers’ job performance. Data analysis was done using SPSS software. The study found there was a significant relationship (χ2 = 35.611, p=0.00) between leadership styles and teachers’ job performance. The researcher concluded principals practice various leadership styles. The researcher also concluded that supportive leadership style affects teachers’ performance. The researcher recommended that the government and local leaders should sensitize parents in cooperating with the school principal in improving academic performance