ABSTRACT Although women's outsized share of household labor and subsequent career disadvantages are well‐documented, the impact of income arrangements within dual‐earner couples has been underexplored in the context of the work–family dynamic. Drawing upon resource and gender construction theories, we examine how income dynamics within male–female dyads can differentially affect each partner's career success via unpaid home labor. Using multilevel polynomial regression on a longitudinal sample of 7252 dual‐earner couples over a 22‐year period from the Household, Income, and Labor Dynamics in Australia (HILDA) Survey, we demonstrate that the interplay of income within these dyads differentially shapes partners' household labor, ultimately influencing female (but not male) career promotion. Specifically, women face a lower likelihood of promotion when in male‐ and female‐breadwinning arrangements compared with dual‐breadwinning arrangements with minimal resource differentials, partly due to the increased household labor. Among dual‐breadwinning arrangements, we find that female partners have a higher chance of promotion when male partners have similarly high (versus low) income levels, due to reduced household labor. Our supplementary analysis uncovers that work centrality accounts for the gendered impact of household labor on promotion while also illustrating how the effect of income arrangements evolves over 22 years. Overall, our findings provide new revelations on how breadwinning arrangements within couples can reinforce or hinder women's career advancement, while largely leaving men's careers unaffected, through the gendered spillover effect of unpaid household labor.