<p>The rapid pace of infrastructure development demands the maximum utilization of locally available soils, regardless of inherent nature. This leads to essential stabilization of problematic soils to make it suitable for the geotechnical engineering purposes. This study explores a sustainable approach to enhancing the engineering properties of silty soil from the Kuttanad region stabilized using weak/fragile biochar as well as using geopolymer activated biochar. Coarse biochar was tested at varying dosages to evaluate their impact on geotechnical parameters of collected silty soil. It showed a marginal strength improvement from 100 to 120&#xa0;kPa up to an optimum dosage of 6%, beyond which strength declined up to 15%. Further, a parametric experimental investigation on treatment of soil utilizing optimal coarse biochar with alkali-activated geopolymer (NaOH &amp; Na₂SiO₃) binder of varying concentration was commenced to enhance shear strength parameters. Geopolymer-stabilized soils showed noticeable gains in unconfined compressive strength (312&#xa0;kPa) with marginal improvement in compressibility and permeability aspects. Absolute arrest of desiccation cracks under extreme environments was also observed due to geopolymerization. Hence, the synergistic effect of biochar with alkali-activated geopolymer binders could be an eco-friendly solution for stabilizing silty soils in Kuttanad. Leachate analysis of geopolymerized soil also lies within the permissible limit. However, additional measures are further needed under repeated wetting-drying to reduce the strength loss from 35 to 20% to enhance the durability characteristics.</p>