Employee retention is a crucial indicator for the educational sector all around the world for enhancing the quality of education provided to the students. This study is conducted for understanding the importance of two very important factors that are related to the employee retention levels in the private schools of Nigeria. These factors as considered include the high-performance work systems implemented in these schools and the job stress levels of the employees of the private school in the chosen region of the study. The study has derived different conceptual constructs under the bracket of these two variables with the help of the theoretical foundation of Affected Event Theory (AET). The study has developed six different hypotheses based on the relationships between the constructs of the independent variables and the dependent variable of employee retention. A questionnaire has been formulated for collecting responses as relevant data for the data analysis of this quantitative study from a sample of 254 academic staff of these private schools in Nigeria. The data collected has been further analysed using the IBM SPSS software to conduct tests such as reliability, multiple regression and more and the research questions have been addressed to provide different future scope that this study can provide for other research done on similar study topics.