Human well-being is a core global issue. Thus, achieving and sustaining higher levels of well-being is a challenge for citizens, governments, and international organizations worldwide. The present study aimed at describing the well-being status of residents of Tehran municipal districts. To achieve this, a composite well-being index was constructed for 22 municipal districts of Tehran (Tehran Well-being Index; TWI). This cross sectional study was conducted from May to October 2017 in Tehran using the data collected in the second round of Urban Health Equity Assessment and Response Tool (Urban HEART) Project of Tehran (2012-2013). The statistical population of this study was 22 municipal districts of Tehran and a sample of 34 700 households (118 000 individuals) selected using multistage cluster sampling. TWI was developed through the Organization for Economic Cooperation and Development (OECD) methodology of constructing composite indicators. Then, 22 municipal districts were categorized based on TWI scores. All data were analyzed using SPSS v.18. In addition, a cartogram was applied using GIS software to classify well-being status among Tehran municipal districts. Factor analysis results showed that the Kaiser-Meyer-Olkin (KMO) value was 0.691 and 2 factors (material well-being and psychological well-being) explained 74.13% of the total variances. Furthermore, the best and worst performances were found in districts 6 and 17, respectively. District 6 had the best and district 17 the worst material well-being status. Also, districts 6 and 19 had the best and worst psychological well-being status, respectively. In general, the well-being status of the municipal districts of Tehran can be divided into 5 main categories: (a) prosperous (districts 1, 2, 3, 5, and 6); (b) fairly prosperous (districts 4, 21, and 22); (C) moderately prosperous (districts 7, 8, and 13); (d) less prosperous (9, 10, 11, 14, and 12); and (e) deprived zone (districts 12, 15, 16, 17, 18 and 19).