Research on delayed transitions to adulthood in East Asia has largely focused on late marriage, low fertility, and unstable employment. Extending this literature, we propose household headship as a simple yet sociologically meaningful indicator of a successful transition to adulthood and use it to investigate long-term trends among young adults aged 20–44 in five East Asian societies: mainland China, Hong Kong, Taiwan, Japan, and South Korea. Our analysis reveals a substantial decline in young men’s chances of heading the households, alongside a steady increase in headship rates among young women, leading to a marked narrowing of gender gaps in becoming a household head. Results from JMP decomposition show that these gendered trajectories over the past four decades are primarily driven by two processes: young men’s relative setbacks in leaving the parental home and young women’s relative gains in achieving economic independence. However, this encouraging narrative of women’s empowerment within families is notably weaker in Japan, arguably because unmarried young men are far more likely than unmarried young women to live alone. By documenting changing patterns in who becomes a household head and when, our findings underscore the need to reconceptualize independent adulthood in the context of eroding patriarchal family structures across East Asian societies.