<p>Urban trail networks have garnered widespread attention for their contributions to sustainable urban development and residents’ health and well-being. Addressing the current lack of research on mountainous cities, this study develops an integrated analytical framework to examine the relationship between Walk Score and environmental factors along urban trails, using Chongqing’s central urban area—a representative mountainous city—as the case study. By employing the Geodetector model, the study quantifies both the individual and interactive effects of environmental variables on trail-based walkability. The findings highlight that Building Height (BH), Proportion of Impervious Surface (PIS), and Number of Attraction Reviews (NAR) significantly affect Walk Score. More importantly, the interaction between BH and Population Density (DP) shows the highest explanatory power, indicating that combinations of environmental factors may exert greater influence than any single variable alone. This also suggests that less-studied factors—such as the proportion of water bodies and public perception indicators like NAR—can meaningfully contribute to walkability under complex terrain conditions. This study further establishes a spatially explicit and interaction-sensitive analytical framework to evaluate trail-based walkability in mountainous urban settings. By incorporating multiple environmental factors and their interactive effects, the research not only advances methodological approaches but also offers practical insights for urban trail planning. The findings highlight the importance of multifactorial, coordinated planning strategies in fostering inclusive, healthy, and sustainable urban walking environments.</p>