Urban green spaces (UGS) are key elements of placemaking, contributing to ecological balance, public health, and social cohesion. In post-socialist cities, however, their potential to foster social interaction remains largely underutilized. This paper examines the discrepancy between planned and realized functions of UGS in Niš, Serbia. The analysis combines planning documents, legal frameworks, and field observations to trace the effects of post-socialist transformations such as restitution, privatization, and deregulation. These processes have led to the loss, fragmentation, and inadequate maintenance of green areas, reducing their capacity to support community life. To illustrate these dynamics, the paper presents selected case studies: Krive Livade, Somborska–Studenička, and Vagres City, along with recent initiatives aiming to restore the social role of green spaces. The examples highlight a shift from socialist-era planning, which prioritized collective open areas, toward contemporary market-driven development that often undermines greenery and social use. Findings indicate that UGS in Niš face challenges of underuse, poor management, and spatial degradation. The paper argues that effective placemaking requires not only spatial and ecological planning but also institutional support, community participation, and coherent implementation, without which UGS cannot realize their role as spaces of interaction, identity, and resilience.