This study focused on Principal professional competencies as predictors of job performance of teachers. Two research questions were raised and four hypotheses were formulated to find out the level of principals’ competencies on human and materials resource management The researcher reviewed relevant literature to establish the theoretical bases for the study. The descriptive survey research design was adopted for the study. Through multistage sampling procedure (simple, purposive and disproportionate random sampling techniques), four states in the southwest geo-political zone of Nigeria were selected for the study. One thousand two hundred (1,200) respondents comprising of 816 teachers, 384 principals were selected as sample. The research instrument used for data collection was an adapted questionnaire titled: Principal Professional Competencies on Human Resource Management Scale (PPCHRMS) and Principal Professional Competencies on Material Resource Management scale (PPCMRMS). The instruments were subjected to face and content validity and Cronbach Alpha reliability estimates of .858, and .842 obtained. The data collected were analyzed using descriptive statistics of mean and standard deviation for the stated research questions. Regression and t-test statistics were used for the stated hypotheses tested at 0.05 level of significance. The mean difference in the opinion of the principals and teachers regarding human resource were higher for principals (M= 2590.76, SD= 244.459) than teachers (M=2590.459, SD= 237.300), t(1198)=.035,p>.05. Levene’s test indicated equal variance assumed (F=1.059, p=.304). Also, the mean difference in the opinion of the principals and teachers regarding material resource were lower for principals (M= 1848.23, SD= 1277.304) than teachers (M=1951.28, SD= 1246.818), t(1198)=1.325,p>.05. Levene’s test indicated equal variance assumed (F=3.423, p=.065). Hence, the major finding of the research indicated that the principal professional competencies showed high level of professionalism in human and material resource management and were significant to teachers’ job performance. Recommendations were made such that principals should ensure planning and distribution of human and material resources are available in the school before resumption and that teachers should be shouldered with some responsibilities in the schools.