Objective We assessed the association between household decision-making and mental well-being among Asian immigrant women residing in Korea. We also investigated if the impact varies by the regional origin and examined potential factors for joint decision-making. Methods We conducted a cross-sectional study using the Korean National Survey of Multicultural Families 2015 and logistic regression. We analyzed data from 11,188 married immigrant women ages 20 to 59 who were originally from East Asia or Southeast/South Asia and coliving with their spouses. We defined households as joint-decision, wife-decision, or husband- decision based on who decides how living expenses are spent. Mental well-being encompassed a depressive mood for two consecutive weeks, and life and marital satisfaction. Results After controlling for covariates, we showed that immigrant women in husband-decision households were more likely to have depressive mood (odds ratio [OR] 1.26, 95% confidence interval [CI]: 1.14-1.38), poorer life satisfaction (OR 1.49, 95% CI: 1.24-1.78), and poorer marital satisfaction (OR 1.81, 95% CI: 1.47-2.22) than women in joint-decision households. Immigrant women in wife-decision households had a similar but slightly lower odds of poor mental well-being. This association was less prominent for Southeast/South Asian origin than East Asian origin, while the age-adjusted prevalence rates of poor mental well-being among them were higher than their East Asian counterparts. Factors that restricted the odds of husband-decision did not necessarily guarantee wife-decision. Conclusions This study suggests one-sided decision-making can be a risk factor for immigrant women's poor mental well-being, while joint decision-making is protective. Differences across regional origins suggest domestic decision-making might be a less important predictor for mental well-being in immigrants more occupied with adapting to the host society. Factors for joint decision-making should be addressed to improve the mental well-being of immigrant women.