Objective Precarious workers have increased over the past two decades in South Korea. Employment instability, especially among young adults, is considered a serious social problem. The unstable employment status of precarious workers has negative impacts on their mental health, such as suicidal behavior. This study aims to identify the effect of the unstable employment conditions on the suicidal behavior of precarious workers. Methods An online survey was conducted with a panel sample of South Korean adults (n=797) who were precarious workers aged between 25-34 years. We applied Model 6 of SPSS PROCESS MACRO 3.5 to examine the multiple mediation effects of depression and anger in the relationship between employment instability and suicide. Results Unstable employment had no direct effect on suicidal behavior. The path of unstable employment to suicidal behavior via depression and anger had a significant indirect effect. However, employment and anger were negatively related. The indirect effect of depression and anger on the relation between unstable employment and suicidal behavior was statistically significant. Conclusion This study suggests an association between unstable employment and suicidal behavior, mediated by depression and anger. Specifically, a high level of unstable employment status increased depression. In contrast, a low level of unstable employment status increased anger, which ultimately led to an increase in suicidal behavior. These contrasting findings are likely to reflect the heterogeneity of precarious workers. Further longitudinal studies are necessary to identify the causality between precarious employment and suicidal behavior over time.