Yiwu City, known as the “City of Commerce”, has experienced rapid urbanization, transforming its riverside areas from solely production-focused functions to a “three-dimensional space” that integrates production, living, and ecological functions. This shift has led to increasing demand for recreational and leisure spaces. To support Yiwu’s urban renewal and its shift from “incremental expansion” to “stock optimization”, this study focuses on the city’s waterfront areas. It examines four key factors: user demographics, spatial layout, ecological environment, and urban human-economic factors, breaking down these elements to analyze spatial distribution and vitality. A 23-item evaluation index system for waterfront vitality is established. Using big data sources such as Location-Based Services (LBS), mobile signals, and social media check-ins, combined with Ordinary Least Squares (OLS) for factor selection and Geographically Weighted Regression (GWR) to assess spatial differences, the study also uses a Random Forest model based on deep learning for factor importance ranking. The Shapley Additive Explanations (SHAP) model visualizes these results. The analysis reveals that factors such as transportation node density, functional diversity, shoreline accessibility, and development intensity are positively correlated with waterfront vitality. In contrast, the richness of tourist attractions and property prices are negatively correlated. The study also finds spatial variation across different regions. These findings provide empirical support and recommendations for future waterfront planning, as well as theoretical insights for enhancing urban waterfront vitality.