Characterization of stabilized aggregates through material properties is essential to satiate its design. These material properties comprise of unconfined compressive strength (UCS) and assessment of flexural behavior through modulus of rupture (MoR) and flexural modulus (FM). These properties are strongly affected by the type of stabilizers and materials to be stabilized. The present research highlights the utilization of supplementary cementitious materials (SCMs) like ground granulated blast furnace steel slag (GGBS) and fly ash as a prospective partial replacement to cement in stabilizing aggregates through mechanical tests and its effect on the design process. Changes in material properties with incorporating SCMs were identified and assessed for the subsequent curing periods of 3, 7, 28, and 90 days. Flexural modulus, an essential parameter in the design of stabilized aggregates, was statistically analyzed to identify the effect of using SCMs. Strong linear relationships were found between FM and UCS & MoR (R2 > 0.94). The correlating factors were found to be high for GGBS and fly ash incorporated mixes while less for cement-stabilized aggregates. Further, the cost–benefit analysis for the prospective application of SCMs revealed significant savings of 16 and 6% in cost on utilizing GGBS and fly ash in the stabilized aggregates layer, respectively. The findings from this research are expected to increase the usage of SCMs materials in stabilizing aggregates in high proportion through characterization and economic advantages.