<p>Children’s playgrounds serve as more than recreational spaces—they are dynamic urban environments that mediate intergenerational relationships and reflect the evolving nature of public space. This study investigates the transformation of playgrounds in South Korea through the theoretical lens of Aldo van Eyck’s concept of the “in-between space”. By framing playgrounds as urban mediators between the private and public realms, this research identifies three key spatial dimensions—publicness, multifunctionality, and locality—that define their social and spatial significance. A comparative analysis of representative playground types (park-type, play-type, and experience-type) reveals how contemporary playgrounds reinterpret the spatial and communal functions once embodied by traditional Korean alleyways. Findings highlight that while modern playgrounds maintain a level of openness and accessibility, they increasingly lack multifunctional adaptability and local contextual depth. The study concludes by suggesting strategies for future playground design to recover their role as inclusive urban in-between spaces integrating publicness, diversity, and locality.</p>