Recent research shows that Americans who adhere to Christian nationalism—an ideology that idealizes and advocates a fusion of Christianity and American civic life—tend to hold authoritarian and exclusionary attitudes, particularly regarding ethno‐racial minorities and nontraditional family forms. Such findings suggest a fundamental connection between Christian nationalism and rigid symbolic boundaries, which would likely extend to Americans’ understanding of gender roles. Drawing on notions connecting religious nationalism with defenses of patriarchal norms and utilizing a recent national, random sample of American adults, the current study examines the link between contemporary Christian nationalism and traditionalist gender ideologies. Our analyses reveal that Christian nationalism is the strongest predictor of holding a more traditionalist gender ideology, even after taking into account a host of political and religious characteristics. Moreover, the relationship between Christian nationalism and gender traditionalism holds across religious traditions, including more gender‐egalitarian groups like Mainline Protestants and even the unaffiliated. We conclude by highlighting the implications of these findings for understanding contemporary populist support for Donald Trump, which previous studies have shown is undergirded by both Christian nationalism and sexism.