The valorization of marine biogenic waste represents an important direction in the development of sustainable functional materials. In this study, geopolymer composites incorporating biogenic particles derived from marine shell waste were synthesized and structurally characterized. The biogenic particles consist of calcium-rich crystalline powders (primarily CaCO₃ and CaO phases) obtained through cleaning, thermal treatment, and mechanical size reduction of shell materials. These particles were introduced as functional additives into metakaolin-based geopolymers synthesized from calcined kaolinite (Al₂Si₂O₅(OH)₄) and activated using alkaline solutions (NaOH, KOH and Na₂SiO₃), leading to the formation of a three-dimensional aluminosilicate network. The geopolymerization process resulted in hybrid inorganic composites in which the biogenic calcium-based particles are dispersed within an amorphous aluminosilicate matrix. Structural and morphological investigations were performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to evaluate phase composition, crystallinity and particle dispersion. The results indicate that the incorporation of shell-derived particles influences the microstructure of the geopolymer matrix and contributes to the development of hybrid inorganic composites combining amorphous geopolymeric phases with crystalline calcium-based particles. The results demonstrate that marine shell waste can be successfully transformed into functional additives for geopolymer materials. This approach contributes to waste valorization while enabling the development of sustainable geopolymer composites with potential applications in environmentally friendly construction materials and environmental remediation technologies.