In August 2019, a landslide struck a part of National Highway 547, Madhya Pradesh, India. Half carriageway width washed away on the downhill side, while the uphill remained intact. In August 2020, the highway was reinstated by re-filling the settled mass with a gabion wall and mattress for confinement. However, in the same month, the hillslope failure reoccurred, resulting in the settlement of half carriageway width and the bulging and settlement of the gabion wall. Subsequently, a thorough investigation was carried out using borehole and geophysical tests. Considering the site’s geometry and the failure’s repeatability nature, three-dimensional (3D) finite element analysis was performed to identify the cause of the failure. This paper discusses the 3D modeling of the hill slope, considering key parameters to create a realistic numerical model, and adopts seepage-coupled slope stability analysis. In addition, the results of the 3D model were compared to their equivalent 2D model. Site investigation revealed four-layer subsoil stratification varying between topsoil to moderately weathered rock. The seepage analysis displayed the development of the phreatic surface that fluctuated with monthly rainfall and indicated the highest degree of saturation in August. The strength reduction method analysis yielded a FoS of 1.2, surpassing the 2D result of 1.0 obtained during August rainfall. The evaluation of soil nails as remedial measures showed a factor of safety of 1.3 in the 2D model, which increased to 1.45 in the 3D model and was subsequently implemented at the site.