Despite undergoing high economic development, Korea is known for having relatively low levels of happiness. However, research on happiness in Korea is limited due to a lack of data. To address this, we conducted the “Korean Happiness Survey” to ① track happiness levels and inequality among Koreans, ② predict various social phenomena, ③ and clarify various determinants that influence levels of happiness and inequality, and ④ increase overall happiness in the country. In 2023, the third wave survey was conducted targeting approximately 7,500 households, and 17,000 citizens aged 15 or older. The average levels of happiness scored for Koreans in 2023 was 6.56 points out of 10. We also found lower happiness scores among vulnerable groups, highlighting the significant issue of inequality in happiness. To address this problem, it is important to implement policies that can improve the quality of life and therefore increase happiness for these disadvantaged groups.