This study examines whether and how the association between religious homogamy (i.e., whether spouses have the same religious affiliation) and marital satisfaction varies across religious affiliations by utilizing a unique context that four large religious groups (i.e., Buddhists, Protestants, Catholics, and religious nones) coexist in South Korea. Our results show that while religious homogamy has a positive relationship with marital satisfaction among Protestants and Catholics, there is no such association among Buddhists. This study also reveals that higher levels of religious attendance intensify the positive relationship between religious homogamy and marital satisfaction only among Protestants. Moreover, religious heterogamy is positively associated with marital relationships among religious nones compared to religious homogamy. However, this pattern held only for religious nones who married Buddhists or Catholics. We discuss the implications of our findings for research on religion and marriage from cross‐cultural perspectives.