This study examined the relationship between occupational stress and academic staff productivity in public tertiary educational institutions in Lagos State, with two tested hypotheses. With the study’s foundation anchored on correlational and descriptive research designs were adopted, its population comprised all academic staff in public tertiary educational institutions in Lagos State. The sample size was 700. Questionnaire was used to collect data after ensuring its validity and establishing their reliability using test- retest method. The questionnaire is named “Occupational Stress Questionnaire for Teachers” (OSQT). Analysis was carried out using inferential statistics of Pearson’s Product-Moment Correlation Analysis and Regression Analysis by using the Statistical Package for Social Science (SPSS) version 24.0. Findings indicate that there is no significant relationship between occupational stress and productivity among academic staff in public tertiary educational institutions in Lagos State; also, the findings shows that there is a significant difference in the extent to which the identified factors of teaching (workload), research and publications, and community service are responsible for occupational stress among academic staff in public tertiary educational institutions in Lagos State. It is concluded that occupational stress has a considerable influence on the lecturers’ productivity in tertiary educational institutions in Lagos State. The study therefore recommended that tertiary educational institution managers should ensure that lecturers are assigned duties in line with their carrying capacities.