The physical expansion of peripheral settlements in metropolitan areas, particularly in southwest Tehran, is shaped by complex interactions among economic, demographic, managerial, and geographical factors. Identifying these driving forces is essential for sustainable urban development management. This study aims to identify and prioritize the factors affecting peripheral expansion using an applied-developmental approach and descriptive-analytical survey method. The statistical population consisted of 40 experts, academics, and urban managers familiar with the study area, selected through purposive sampling. A researcher-developed questionnaire, comprising 40 factors classified into four settlement categories, was employed for data collection. These factors were assessed across two dimensions - influence and intervention capability. Data analysis was performed using the Friedman test, ANOVA, and strategic matrix analysis. The findings revealed that “strategic location and proximity to Tehran” had the highest influence with a mean score of 4.50. The fourth settlement group, including Qods, Andisheh, Parand, and Shahriar, recorded the highest influence (mean=4.02), while the first group had the lowest (mean=3.05) (F=8.74, P<0.001). The Friedman test confirmed significant differences among the factors (χ²=42.36, df=9, P<0.001). Strategic analysis indicated that managerial and legal factors, particularly infrastructure development and municipal performance, require immediate intervention. Four key drivers were identified: strategic location, government investment, land shortage in Tehran, and escalating housing prices. Based on critical uncertainties, four scenarios were developed for 2046, including guided sustainable growth, unbalanced growth, resource-constrained managed development, and uncontrolled accelerated growth. Finally, an operational matrix was proposed to support sustainable management of southwest Tehran’s future development through integrated spatial planning.