Across both Europe and East Asia, growing cultural diversity is profoundly reshaping social life. This shift is unfolding within a global context shaped by two primary trends: first, a “differentialist turn,” in which states increasingly move away from traditional ideals of cultural homogeneity and acknowledge their responsibility to accommodate minority claims; and second, the ascent of cities as pivotal actors within a complex landscape of multiscale governance. These two processes are intimately connected, with certain cities—rather than national governments—emerging as key stakeholders and innovators in diversity governance. This chapter explores how diversity governance is evolving in Europe, Japan, and South Korea, paying particular attention to the role of “diverse cities” as dynamic agents of change in multiscalar environments. It begins by examining how the differentialist turn has unfolded in these distinct geographical contexts, then compares the processes of diverse city-making in three exemplar cities—Barcelona (Spain), Hamamatsu (Japan), and Ansan (South Korea)—each recognized as a leading laboratory of diversity governance at both national and international levels. Ultimately, this study highlights the potential for diverse cities in Europe and East Asia to serve as crucial junctures where national and transnational multicultural approaches intersect, evolve, and find concrete expression.