In recent decades, migration as the temporary or permanent relocation of individuals from one place of residence to another has exerted significant impacts on urban management, spatial balance, and the structure of metropolitan areas. Tehran, as the largest metropolis in Iran, has experienced a sharp rise in housing prices and intensifying spatial inequalities, creating the conditions for migration from the urban center to the periphery. This process has increased pressure on surrounding areas and generated challenges for sustainable urban development. Therefore, a systematic identification of the causes of this movement is essential for the formulation of effective policies. The present study aims to identify and analyze the causes of migration from the center to the periphery of Tehran, considering the city of Tehran as the center and its surrounding urban agglomeration as the periphery. The research was conducted using a qualitative approach and thematic analysis. Data were collected through semi-structured interviews with 20 experts in the fields of geography, urban planning, and policymaking, and were coded and analyzed in MAXQDA software through six stages. The findings indicate that economic factors (livelihood pressures), institutional factors (inefficient housing policies), physical factors (metro development and improved accessibility), environmental factors (air pollution), and socio-cultural factors (retirement) are the main drivers of this migration, often operating in a combined and synergistic manner. Effective management of this process requires coordinated and integrated policies in housing, transportation, urban services, and quality of life improvement to achieve spatial balance.