This study examines the typology and operating mechanisms of urban regeneration libraries by defining them not merely as cultural facilities or information service institutions, but as social infrastructure and practical anchors for restoring declining and fragmented local communities. Based on a qualitative case analysis of domestic and international libraries related to regional and urban regeneration, the study analyzed location characteristics, modes of asset reuse, regeneration goals, spatial composition, services and programs, governance structures, and contributions to local revitalization. The analysis identified six major types of urban regeneration libraries: city-center public space and city-branding type, social inclusion and neighborhood recovery type, idle-space conversion and neighborhood regeneration type, industrial heritage and large-scale regeneration anchor type, commercial and public-private mixed-use type, and hybrid-complex type. The findings show that these libraries generate regeneration effects through six operating mechanisms: restoring access to information, culture, and learning; enabling non-commercial stays; forming social networks; reconstructing place memory; promoting local economic and creative activities; and establishing collaborative governance. This study argues that libraries should be understood not as auxiliary facilities within urban regeneration projects, but as core public infrastructure that reorganizes local publicness, accessibility, social relationships, place identity, and sustainability.