This study introduces the design and realization of an electrothermal-enabled reinforcing grid based on mineral-impregnated carbon-fibers (MCFs) for efficient and low-power-consuming de-icing of a geopolymer (GP) concrete surface. Initially, carbon fiber (CF) yarns were impregnated with a GP suspension through a custom-made production line. Then, particular fresh MCFs were further processed via vacuum bagging, resulting in two different profile shapes with differentiated mechanical and physicochemical properties. The as-produced MCF structures were assessed regarding their electrothermal performance whereby the most efficient were employed as heating elements for assembling the reinforcing grid as Joule heater device. The obtained multifunctional reinforced concrete composite demonstrated de-icing effectiveness for an applied DC voltage of 2.2 V, corresponding to a surface temperature of 45 °C with a significantly low required heating power of 95.6 W/m² in relation to similar studies. The experimental work was validated using a coupled field of electrothermal modelling. The proposed modular design offers unique potential and flexibility for large-area uniform and responsive de-icing applications via multiple interconnected multifunctional reinforcing grids.