Underemployment, an increasing problem of almost whole countries, is an economic indicator, working between unemployment and employment. Although underemployment is an economic indicator, it negatively affects job life. When the relevant literature is examined, it is seen that studies examining the effects of underemployment on job life mainly focus on the "overqualification" dimension. This study aims to investigate the relationships between all sizes of underemployment and turnover intention. According to Turkish literature on labour economics, this is the first study to examine the relationship between five dimensions of underemployment and turnover intention in Turkey. The data obtained using the survey method were analysed by statistical methods such as Exploratory Factor Analysis, Kruskal Wallis H, Mann Whitney U, Spearman Correlation Analysis. The empirical results show a significant and positive link between overqualification-underemployment and turnover intention. All the study’s hypotheses were accepted, and implications were discussed.