This study investigates the ability of vetiver grass (Chrysopogon zizanioides) to improve the geomechanical characteristics of fine soils in the province of Loja, Ecuador. Given the problem of erosion and slope instability in the region, the effect of the vetiver root system on soil shear resistance was experimentally evaluated. Undisturbed soil samples were extracted, both with the presence of vetiver and control (without vetiver), at depths between 0.80 and 1.5 m. Laboratory tests included physical characterization of the soil and geomechanical tests such as the undrained consolidated triaxial test (CU) and the direct shear test (CD). The results obtained demonstrate a notable increase in the apparent cohesion and shear resistance of the samples with vetiver roots compared to the control samples. The presence of vetiver markedly enhanced the soil’s shear resistance capacity, reflected in a considerably greater apparent cohesion in the reinforced samples. These findings validate vetiver grass as an effective and sustainable bioengineering solution for slope stabilization and mitigation of erosive processes in soils with characteristics similar to those studied.