Employees spend fifty percent of their lives in indoor workplace environments, which greatly influence their mental status, reactions, and performance. Therefore, organisations are responsible in creating a stress-free work environment for their employees to perform well while maintaining their physical and psychological well-being. Thus, the purpose of the current study is to identify the impact of occupational stress on employee performance in plantation industry, Sri Lanka. Respectively, the researchers looked at the research problem in a positivist view by utilising deductive reasoning to collect quantitative (survey design) data. The target population was 110 employees in which 82 sample size was decided based on Krejcie and Morgan (1970) sample size table and chosen utilising simple random sampling. However, the data was collected from 81 employees of a prominent organisation in plantation industry. Our results suggested a significant positive relationship (r = .978, p<.01) between occupational stress and employee performance by accepting main alternative hypothesis. The findings have implications for researchers and managers in plantation industry