Given the increasingly unstable labor market, South Korean young adults are facing a variety of difficulties. This study investigates health, financial, psychological, and social factors affecting happiness among South Korean young adults in poverty. Using a sample of 722 young adults in poverty receiving welfare benefits, multiple regression analysis results indicate that financial stress, employment hope, perceived health condition, social capital, family support, and resilience are significantly associated with happiness level. Particularly, the psychological and social factors are strongly associated with happiness. These findings highlight the necessity and importance of intervention to empower psychological strengths and social relationships to improve happiness among vulnerable young adults in poverty.