The challenges encountered for the infrastructure development in regions with soft soil cause construction delays, leading to additional expenses. Implementing geosynthetic reinforcement at the foundation level can improve embankment performance. In the Palsit–Dankuni highway widening project (NH-19), the existing soil consists of very soft and compressible clay. This section of the project requires a high embankment with a reinforced earth (RE) wall. A unique ground improvement technique has been adopted, using fly ash, a granular layer, and geogrid as basal reinforcement to improve the bearing capacity and stability. This method involves replacing poor soil up to 4 m deep within the RE zone with fly ash wrapped in geogrid, a layer of granular soil at the top and bottom of the fly ash fill, and a layer of geogrid basal reinforcement across the roadway’s entire width at the base of the embankment. In this paper, the performance of an 8.5 m high RE wall constructed on the improved ground in this stretch is numerically investigated using the Finite Element tool with PLAXIS 2D. Another two models of RE wall on modified ground without basal reinforcement and without ground improvement are also analyzed to evaluate the effectiveness of the adopted ground improvement technique. The present investigation reveals that the ground modification method adopted in this study significantly reduces the settlements and excess pore water pressure to 63% and 50%, respectively. Also, use of basal reinforcement improves the structure’s stability by reducing the lateral deflection of the RE wall by 82%.