The ballast layer is discrete in nature, and it undergoes degradation and deformation upon application of repeated train loading. Whereas the ballast treated with polyurethane (PU) has shown improved shear strength, degradation and deformation reduced significantly. The current study assessed the behavior of PU-stabilized ballast based on large-scale direct shear and cyclic loading tests. The large-scale direct shear tests were conducted on ballast stabilized with a varying polyurethane content (1.5%, 2.25%, 3%, and 3.75%) at normal stresses (σn) of 80 and 120 kPa at a shearing rate (Sr) of 9 mm/min. The direct shear test results indicated that for the polyurethane content above 2.25%, the increase in shear strength was found to be marginal. The friction angle and dilation angle of polyurethane-stabilized ballast increased from 64º to 70º and 12º to 15º, respectively, as the polyurethane content increased from 1.5% to 3.75% (σn = 120 kPa; Sr = 9 mm/min). Further, cyclic tests were conducted on untreated and ballast treated with 2.25% at a loading frequency (f) of 32 Hz. The test results indicated that the polyurethane treatment has significantly reduced the vertical and lateral deformations of ballast. The current research also highlighted that polyurethane stabilization enhances the track life and reduces the maintenance costs.