The health impacts of the development and environment have been widely assessed, but little is known about the impact of physical characteristics of urban planning on people's mental well-being. Thus, this research is crucial to understand the mental health challenges of urban population in Malaysia. The objective of this research is to examine the influence of urban planning on mental health, particularly the attributes of urban planning, density and land use, as well as their potential relation to psychological stress, depression and anxiety. The study was carried out at low-cost flats at Pantai Dalam in Federal Territory of Kuala Lumpur. Besides the secondary data collection and site observation, a survey in a form of questionnaire that used Depression Anxiety Stress Scale (DASS-21) was distributed. The findings showed that density and land use contributed to mental disorders. The research findings can be applied by government agencies, professionals and private sectors to plan healthier urban physical environment. This research will add to the growing literature that suggests the importance of the built environment in shaping mental health.