This chapter outlines the research design and methodology for empirically examining the relationship between the built environment and residents’ subjective well-being (SWB) in high-density urban areas, with Guangzhou’s central urban district as the case study. It aims to provide a rigorous, multi-method framework for measuring both subjective perceptions and objective built environment features, and to delineate the pathways through which environmental factors influence SWB. Section 6.1 introduces the study area—characterized by high population and building density—and details the multi-stage stratified sampling procedure. Section 6.2 elaborates on the measurement of core variables, including Life Satisfaction (SWLS), Perceived Environmental Quality, Social Capital, and optimism (LOT-R), using validated scales and Likert-type instruments. Section 6.3 reports pilot testing and item discrimination analysis. Section 6.4 assesses the reliability and validity of all instruments. Section 6.5 describes formal data collection—including geocoding and the use of 1000 m network buffers to address geographic context uncertainty—and integration of multi-source geographic data. Finally, Section 6.6 outlines analytical strategies, including correlation analysis, regression, structural equation modeling (SEM), and Bootstrap mediation tests. This chapter establishes a robust empirical foundation for identifying built environment interventions that enhance well-being in high-density urban contexts.