Nigeria’s agricultural sector is pivotal to its economy, yet it grapples with substantial environmental challenges, concerning the management of Agro-wastes such as rice husk which constitute about 60 % of total paddy rice. With millions of tons of rice husk generated annually, the traditional burning of this waste not only constitute to environmental degradation but also poses serious health risk due to emission of CO₂ and particulate matter. This study explores the conversion of locally sourced rice husk ash into nanosilica to enhance the mechanical properties of Nigerian tropical soils for road construction. Various proportions (0%, 1%, 2%, 3%, 4%, and 5%) of nanosilica were incorporated into the soil, and tests including particle size distribution analysis, Atterberg limits, standard Proctor compaction, California Bearing Ratio (CBR), and unconfined compression tests were conducted. Transmission Electron Microscopy (TEM) confirmed the nanosilica's particle size range (1-9 nm), predominantly within 1-7 nm, indicating its efficacy as a reactive pozzolana. Results revealed significant improvements in soil characteristics, with CBR increasing from 5% for natural soil to 14% at 3% nanosilica replacement, and unconfined compressive strength rising from 0.09 MPa to 0.26 MPa under similar conditions. This research underscores the potential of converting agricultural waste into valuable nanosilica for sustainable soil improvement, highlighting keywords such as waste to wealth, sustainability, tropical soils, climate action, and nanotechnology.