The aim of this article is to demonstrate a novel polymer‐based technique for stabilization of soil against wind and water erosion. Conventional approaches deal with individual water‐soluble polymers, which, being deposited on the soil, are removed from the soil surface after rewatering. Here, we describe an elegant way for soil stabilization via deposition of interpolyelectrolyte complexes formed by two oppositely charged water‐soluble polymers. Electrostatic complexation in an aqueous solution of a cationic poly(diallyldimethylammonium chloride) with an excess of water‐soluble anionic biopolymers, humic acids, results in formation of a negative non‐stoichiometric interpolyelectrolyte complex (NIPEC). Upon deposition of a NIPEC aqueous solution over soil and drying out, a protective layer (crust) forms on the surface, composed of NIPEC and soil particles, resistant to wind and water erosion. After destruction, the crust is completely restored by rewatering. The high stability of the NIPEC‐soil crust is due to a NIPEC block structure with hydrophilic free anionic units and hydrophobic mutually neutralized anionic/cationic units, which ensures optimum adsorption on the surface of soil particles and binds them to bigger aggregates. The NIPEC treatment retains the porous structure of soil that favors seed germination and plant development. Being effective absorbent of heavy metals, the NIPEC formulation ensures a normal seed germination in the presence of toxic Cu2+ ions. Thus, the humics‐based NIPECs ensures antierosion protection and detoxification of soil. Additionally to ecological and agricultural applications, the NIPEC formulations have potential for immobilization of moving sands, conservation of mining dumps, treatment of road slopes, and so forth.