This study aims to examine how the aging population of each region has changed from 2009 to 2018, and how age-friendly the current neighborhood environments are in those areas in Daegu, Korea. The 139 administrative units are used as spatial units to identify aging regions, while 100 m × 100 m grid cells are employed as spatial units to capture the environmental variables of the neighborhood comprehensively. To analyze Daegu’s aging regions, emerging hotspot analysis was performed, demonstrating the spatio-temporal patterns of the elderly population. ANOVA analysis and a case study with field surveys were used to examine the age-friendly environmental conditions in aging regions. Findings of this study showed that Daegu’s aging regions were increasing rapidly and spreading from the city center over time. In addition, it was found that the neighborhood environmental conditions of the aging regions were very poor in terms of accessibility, safety, and pleasurability. Significant differences were also found in the levels of age-friendliness of the neighborhood environments, depending on whether they are urban or suburban. The results herein support public policy proposals relevant to urban planning, environmental design, and aging policies.