Considering the three major problems of energy, raw material shortage, and waste, the development of environmentally friendly building materials is one of the development programs in the field of civil engineering. This study investigates the use of industrial and agricultural wastes in the development of sustainable clay blocks through activated geopolymerization technology with synthesized sodium silicate. Kaolinite clay was used as the initial matrix and supplemented with industrial fly ash, rice husk ash, and natural sands to synthesize sodium silicate additive. The alkaline activator was synthesized from silica sand through an optimized dissolution process with sodium hydroxide, and the SiO₂/Na₂O molar ratio was 1.5 and the H₂O/Na₂O ratio was 10. The samples were tested under different curing conditions and different concentrations of synthetic sodium silicate in clay blocks with different percentages of waste (0.5, 1, and 1.5%). Key findings show that: (1) compressive strength increased by 21–24% with 30 cc of alkaline activator at 150°C curing. (2) optimal substitution of 1% rice husk ash yielded maximum strength (1.81 MPa) that outperformed fly ash; (3) longer curing increased strength by 18–30% in 7-day specimens due to complete geopolymerization; (4) silica sand-derived activator was economically viable. The results confirm that waste-derived geopolymers reduce energy consumption while utilizing industrial/agricultural byproducts and provide a scalable route to environmentally friendly construction.