Transit-oriented development (TOD) offers a planning basis for compact, mixed-use, and vibrant station areas. However, in many rapidly developing Chinese cities, metro-network expansion has not been matched by coordinated station-area commercial renewal, resulting in spatially uneven street-level activity despite improved transit accessibility. Taking the North Ring Road Station area in Changchun, China, as a case, this study examines the associations between TOD-related spatial conditions and observed human activity intensity as a proxy for commercial spatial vitality, and how these spatial associations can inform targeted regeneration strategies. Within an 800 m TOD analytical boundary, commercial point of interest (POI) data, Baidu Heatmap-derived human activity data, building footprints, road-network data, land-use information, and field observations were integrated. Average nearest-neighbor (ANN) analysis, kernel density estimation (KDE), standard deviational ellipse (SDE) analysis, ordinary least squares (OLS) regression, and geographically weighted regression (GWR) were applied within a 5D TOD framework. The results reveal a dual-core, corridor-oriented, and spatially uneven commercial structure. Commercial facility agglomeration and functional diversity are positively associated with observed activity intensity, whereas transit distance, road-network configuration, building morphology, and proximity to commercial anchors exhibit spatially heterogeneous associations. These results suggest that transit proximity and commercial concentration alone do not necessarily correspond to spatially continuous activity when pedestrian permeability, interface openness, and functional mixing are limited. The study translates these associations into evidence-informed transport-development responses that coordinate metro-entrance access, pedestrian transfer and first/last-mile connections, commercial functions, and surrounding land uses, thereby providing a micro-scale diagnostic approach to station–street–commercial integration.