Physical inactivity and unhealthy eating are considered the primary modifiable risk factors for obesity (ie, obesity-related behaviours). Despite a large body of evidence showing the important role of the built environment in active living, healthy eating, and obesity prevention, research on this topic continues to receive little attention. This is concerning given the alarmingly high and growing global burden of physical inactivity, unhealthy eating, obesity, and noncommunicable diseases (NCD). This Comment aims to shed light on the importance of built environment research for understanding and preventing obesity by summarising the state of the science, identifying research gaps and priorities, and underscoring the ways in which multiple sectors, including the health-care and public health communities, should incorporate built environment approaches to their obesity prevention and health promotion efforts.