<p>The study includes the dynamic characterization of clayey soil blended with nano-SiO₂ and fly ash under cyclic loading at high strain. The percentages of nano-SiO₂ varied between (0.5–7)%, and fly ash varied between (10–30)% by weight of the soil. The optimal dosages of nano-SiO₂ and fly ash were established by employing the outcome of the static test results. The cyclic triaxial (CTX) tests and bender element (BE) tests were carried out to determine the G and D of the composite material and to develop normalized modulus reduction (<i>G</i>/<i>G</i>_max) and damping ratio curves for the same. The strain-controlled cyclic triaxial tests were conducted for a shear strain range of 0.6–3.0% at a loading frequency of 1&#xa0;Hz and an adequate confining pressure of 100&#xa0;kPa. The findings indicated that with the rise in cyclic shear strain (<i>γ</i>), the G decreases while the damping ratio increases. The hyperbolic models were used to build the curve fitting between the <i>G</i>/<i>G</i>_max and the damping ratio curve with various <i>γ</i>. As a result, the correlations between the empirical models fit the database well. The established correlations can be suitable for predicting the seismic behavior of the nano-SiO₂ and fly-ash-treated clayey soil under various strain conditions. Furthermore, the carbon footprint and cost analysis of nano-SiO₂ and fly&#xa0;ash&#xa0;treated clay soil were compared with the traditional stabilizers. The use of nano-SiO₂ and fly ash in stabilizing the clayey soils contributes toward sustainable development and a reduced carbon footprint.</p>