This study aimed to identify the actual and perceived features of neighborhood environments linked to health behaviors and obesity status in vulnerable children by using geographic information systems, walking surveys, and focus group interviews. The participants were 126 children registered at community child centers and 10 mothers of study participants. Increased availability of fast food outlets and convenience stores was significantly and positively associated with fast food and sugar-sweetened beverage consumption and inversely with physical activity. Reduced availability of physical activity outlets was significantly and positively associated with sedentary behaviors. Mothers’ perceptions of their neighborhoods fell into three content categories: (a) changed to be unfriendly for children, (b) adapted to fast food and convenience eating, and (c) confined to physically inactive living. Based on these findings, community-level environmental strategies for reducing unhealthy behaviors linked to neighborhood environments should be prioritized to prevent childhood obesity in vulnerable populations.