This article examines how the meaning of hạnh phúc (happiness) changes across the stages of marriage formation, settlement in Korea, and return to Vietnam among Vietnamese female marriage migrants and their multi-ethnic children. Rather than treating hạnh phúc simply as an individual sense of happiness, the article understands it as a socially and culturally embedded aspiration shaped by family obligations, mobility projects, and institutional conditions. Drawing on secondary demographic statistics and policy documents from Korean and Vietnamese sources (2000–2025), the study develops a transnational analytical framework of hạnh phúc to trace how gendered migration regimes shape migrants’ experiences across the Korea–Vietnam migration corridor. Marriage migration was initially imagined as a pathway to collective family hạnh phúc through economic and social exchange. During settlement, however, hạnh phúc became tied to a regime of conditional incorporation structured around caregiving responsibilities and legal status within Korea’s migration system. Upon return, hạnh phúc is renegotiated through extended family networks and transnational belonging, while remaining constrained by institutional gaps in civil registration, education, and welfare support in Vietnam. The analysis suggests that migration regimes reshape migrants’ understandings of hạnh phúc across different stages of migration while generating new forms of institutional vulnerability that extend beyond national borders.