Rapid development and scale expansion of cities are the core characteristics of the urbanization process, which effectively promote the formation of agglomeration economies, infrastructure sharing, and social mobility improvement. However, it also brings various negative effects such as unequal public services, traffic congestion, and environmental pollution. The principle of isobenefit urbanism proposes that walking accessibility of various service facilities is an important indicator for measuring whether a city is livable, fair, and sustainable. This study specifically examines the impacts of environmental factors on the implementation of isobenefit urbanism in the central urban area of Beijing, a megacity. By obtaining open-source data and performing ArcGIS (10.8.1) analysis, using 183 blocks in Beijing’s core area, we normalized Strava pedestrian heat by road area and regressed it on 12 built environment indicators. The final model (R = 0.650, R² = 0.422, and adjusted R² = 0.381) identifies five significant predictors: block area (β = 0.215, p = 0.001) and average building height (β = 0.299, p = 0.012) are positively associated with walking heat, while building density (β = −0.235, p = 0.003), intersection density (β = −0.321, p < 0.001), and average distance to bus stop (β = −0.196, p = 0.003) are negatively associated. Land use mix and facility supply show positive but nonsignificant effects after controls. These estimates provide actionable levers for isobenefit urbanism in megacity cores.