Large-scale informal recycling networks often emerge among developing economies in response to the challenges of modern urban waste accumulation. South Korea, despite its highly industrialized, developed economy, still maintains an extensive informal recycling sector made up of networks of local junk shops and individual waste pickers. As cities’ large data sources have become more widely available, the use of urban informatics in sustainable smart waste management has become more widespread. In this paper, we use geographic information system (GIS) analysis in order to uncover patterns within Korea’s informal recycling system, looking at the relationship between population demographics, waste levels, and urban planning with the prevalence of junk shops across Korea. We then interviewed junk shop owners, urban planning researchers, and government officials in order to better understand the factors that led to the coexistence of the country’s informal and formal systems of waste management and how junk shops have changed their operations over time in response to recent developments in cities’ urban fabrics. We conclude by giving suggestions for how the usage of urban informatics could increase the efficiency and sustainability of the country’s waste management systems, while also discussing the possible pitfalls of using such existing datasets for future policy decisions.