The study investigated occupational stress and teachers’ job effectiveness in public secondary schools in Obio/Akpor Local Government Area of Rivers State. Descriptive survey research design was used for the study. Three research questions and three null hypotheses were formulated to guide the study. The population of the study consisted of 1,297 teachers in the area. Stratified random sampling technique was used to select a sample of 200 respondents for the study. A self-designed questionnaire titled: ‘Occupational Stress and Teachers’ Effectiveness Questionnaire’’ (OSTEQ) was used for data collection. The reliability coefficient for (OSTEQ) was r=0.73. Mean and standard deviation were used to answer the research questions while Independent sample t-test was used to test the null hypotheses at 0.05 level of significance. The study revealed that stress due to inadequate infrastructural facilities, stress due to excess workload, stress due to students indiscipline negatively influence teachers’ job effectiveness in public secondary schools in Obio/Akpor Local Government Area. And that there is significant difference in the mean rating of male and female teachers on the influence of stress due to inadequate infrastructural facilities, stress due to excess workload, stress due to students indiscipline on teachers’ job effectiveness in public secondary schools in Obio/Akpor Local Government Area. It was recommended among others that; there should be good principal-teacher relationship as well as quiet, cool, clean and beautiful environment that will make teachers to be relieved of their work stress and be effective in their job performance.