Walk Score® is a free web-based tool that provides a walkability score for any given location. A limited number of North American studies have found associations between Walk Score® and perceived built environment attributes, yet it remains unknown whether similar associations exist in Asian countries. The study's objective is to examine the covariate-adjusted correlations between the Walk Score® metric and measures of the perceived built environment in ultrahigh density areas of Japan. Cross-sectional data were obtained from a randomly selected sample of adult residents living in two Japanese urban localities. There was a large correlation between Walk Score® and access to shops (0.58; p < 0.001). There were medium correlations between Walk Score® and population density (0.38; p < 0.001), access to public transport (0.34; p < 0.001), presence of sidewalks (0.41; p < 0.001), and access to recreational facilities (0.37; p < 0.001), and there was a small correlation between Walk Score® and presence of bike lanes (0.16; p < 0.001). There was a small negative correlation between Walk Score® and traffic safety (-0.13; p < 0.001). There was a medium correlation between Walk Score® and overall perceived walkability (0.48; p < 0.001). This study's findings highlight that Walk Score® was correlated with several perceived walkable environment attributes in the context of ultrahigh density areas in Asia.