One of the major challenges in road construction projects is the design and construction of roads over soft and weak soil subgrades. One of the methods to improve the load-bearing capacity of weak foundation soils is reinforcement using synthetic fibers and polymers. Among the most widely used of these polymers is the family of geosynthetics. In this paper, the effect of using geosynthetics to improve the performance of embankments constructed over soft subgrades is investigated. One of the objectives of this study is to introduce the FLAC software as a suitable tool for designing embankments over soft soils. Using the finite difference method and the FLAC software, the settlement of the Urmia–Tabriz road embankment constructed over soft soil was analyzed, both with and without the use of geotextile reinforcement. The settlement values of different layers of the subgrade and embankment were calculated. The results of the analysis show that the settlement values obtained for the unreinforced embankment are in close agreement with the actual field measurements. Furthermore, the results indicate that the use of geotextile reduces settlement by up to 60% compared to the case without geotextile.