Political communication on immigration is often highly moralized, with parties making claims to fundamental beliefs about right and wrong. Yet, what drives parties to use this rhetoric remains unexplored. Contributing to research on parties’ positional shifts on immigration, this study examines their strategic use of moral language in immigration discourse. To this end, we develop multilingual moral dictionaries to analyze parliamentary immigration speeches from eight Western democracies over six decades. While party-level factors do not explain moral language use, increased elite polarization on the issue is associated with greater moralization among all parties. Qualitative analysis shows that moral language is used overwhelmingly to attack political opponents, highlighting its divisive nature. These findings serve as a corrective to the notion that extreme, anti-immigrant, opposition parties are the main drivers of the moralization of immigration; instead, the broader political climate crucially shapes party incentives to (de)moralize.