This study aimed to measure the effectiveness of urban environmental management in improving the security, quality of life, and livability in phase one of the new city of Sahand. The main issue was the gap between management actions and tangible improvements in the security, quality of life, and the mediating role of livability to explain it. The research method is quantitative. Data were collected from 383 respondents randomly. The initial instrument consisted of 54 items in 17 indicators. After exploratory refinement by removing 7 weak items, the final version was stabilized with 47 items. Second-order confirmatory factor analysis and structural equation modeling in AMOS software showed that the composite reliability of all indicators was higher than 0.70 and the average variance extracted was equal to or greater than 0.50. The structural results indicate that the path of urban environmental management to livability is significant and strong (β=0.69). Livability also has a significant effect on the security of quality of life (β=0.74). In contrast, the direct effect of management on the security of quality of life remained invalid (β=0.12). The coefficient of determination for livability was estimated to be 0.48 and for the security of quality of life was estimated to be 0.61. Also, bootstrap with 5000 repetitions reported the indirect effect of management on the security of quality of life to be 0.51 and significant. Among the different dimensions, water and wastewater, governance, green space and sustainable transportation played the greatest role in promoting livability and consequently in improving the security of quality of life. The findings show that management interventions lead to a sustainable improvement in the security of quality of life only if they lead to the daily experience of citizens in accessibility, quality of space, perceived safety and environmental comfort.