We can agree that today the job stands as an important part of our identity. We live in a time when the boundaries between business and personal are becoming increasingly blurred. Home is daily transforming into our office space and changes are taking place constantly. Therefore, it seems even more important to have a detailed understanding of the cause-and-effect relationships that are part of our work routine and those that lead to our work, and for some also life, successes. Namely, we often associate life satisfaction with job satisfaction, and the latter, as it turned out in my research, is intuitively associated with the performance of us as employees. The aim of this master's thesis is to research an employee job satisfaction effectiveness on his work performance. The first part of the master's thesis offers a theoretical overview of both constructs and discovered obstacles in their impact. In order to better understand the relationship between the two variables, a quantitative survey was placed, in which 226 respondents participated. Despite the fact that the last few decades have seen a diverse history of studies in this field, it still offers opportunities for further research and a more detailed understanding of the impact of employee job satisfaction on job performance.