IntroductionThe rapid increase in apartment construction in Australia has raised concerns about the impacts of poorly designed and located buildings on resident health and well-being. While apartment design policies exist, their content varies across jurisdictions and evidence on their impact on health and well-being is lacking. This cross-sectional observational study (2017–2021) aims to generate empirical evidence to guide policy decisions on apartment development and help to create healthy, equitable higher-density communities. Objectives include to benchmark the implementation of health-promoting apartment design requirements and to identify associations between requirements and resident health and well-being outcomes.Methods and analysisEligible buildings in three Australian cities with different apartment design guidelines will be stratified by area disadvantage and randomly selected (~n=99). Building architects, developers and local governments will be approached to provide endorsed development plans from which apartment and building design features will be extracted. Additional data collection includes a resident survey (~n=1000) to assess environmental stressors and health and well-being impacts and outcomes, and geographic information systems measures of the neighbourhood. The study has 85% power to detect a difference of 0.5 SD in the primary outcome of mental well-being (Warwick-Edinburgh Mental Well-being Scale) at a 5% level of significance. Analyses will compare policy compliance and health-promoting design features between cities and area disadvantage groups. Regression models will test whether higher policy compliance (overall and by design theme) is associated with better health and well-being, and the relative contribution of the neighbourhood context.Ethics and disseminationHuman Research Ethics Committees of RMIT University (CHEAN B 21146-10/17) and the University of Western Australia (RA/4/1/8735) approved the study protocol. In addition to academic publications, the collaboration will develop specific health-promoting indicators to embed into the monitoring of apartment design policy implementation and impact, and co-design research dissemination materials to facilitate uptake by decision makers.