Guided by the exchange model, altruistic model, intergenerational solidarity theory, and cultural contexts, this study explored the determinants of financial intergenerational transfers between older parents and adult children in South Korea. We examined 18,820 parent-child dyads by using random-effects models on the first wave of the Korean Longitudinal Study of Ageing (KLoSA) data. Findings showed that downward financial intergenerational transfers were consistent with the self-interest exchange model but upward transfers did not support microeconomic theories. Family solidarity theory was generally supported by downward transfers but geographical proximity was not positively associated with upward transfers. Lastly, cultural contextual variables such as marital status, birth order, and sex of a child were found to be significant. Parents tended to both provide and receive more financial support from unmarried children than from married children. Within the same marital status, the hierarchy existed in order of the first-born son, the second or later sons, and daughters when it came to downward financial transfers. Regarding upward financial transfers, the preference in order was more complicated. The findings of this study help in understanding the intergenerational financial transfers in the Korean context.