ABSTRACT Propelled by issues of migration, globalization, and postcoloniality, the field of collective memory experienced a transnational and cosmopolitan turn in the first decade of the 21 st Century. A broad consensus emerged that memories had become decentralized as nation‐states lost their status as the sole arbiters of the past. Benedict Anderson's “imagined communities,” and Hobsbawm's “invented traditions,” which ascribed nation‐states the power to define and construct mnemonic narratives, gave way to Erll's “traveling memories,” Rothberg's “multinational memories,” and Levy and Sznaider's “cosmopolitan memories.” Scholars even theorized the possibility of creating “prosthetic memories,” a process whereby knowledge of a group's difficult history fosters empathy among outsiders to the group. However, recent populist nostalgia movements observed in the United States, India, Turkey, and China seem to contradict these predictions. As I write in 2025, we are witnessing a movement of inward‐looking, state‐centered memories that delineate clear boundaries between insiders and outsiders. Populists backlash movements have hijacked cosmopolitan impulses, by utilizing languages and tropes the multi‐memory paradigm has helped popularize. This review article explores this reversal by analyzing the aforementioned empirical cases through the lens of cosmopolitanization and calls for comparative research to investigate the link between populist‐nostalgic movements.