The high demand for cement, the challenges associated with the disposal of agricultural waste, and—most significantly—the emission of CO2 associated with cement production and use, which has a negative impact on the environment, have created opportunities for research in the construction sector. The urgent issue for researchers to explore into substitute materials that may sustainably replace cement in the construction sector has also been prompted by the necessity to manage world's natural resources. This paper investigates the properties of hollow blocks produced by replacing cement with Nano-silica produced from rice husk waste at 1%, 2%, 3%, 4%, and 5%, in order to evaluate the effect on the strength of the hollow block. The nanosilicate-crete hollow blocks has four (4) mixes: [1:4, 1:6, 1:8, and 1:10] at different curing days (1, 3, 7, 14, 28, and 56 days by spray of water). The result from the findings showed that the optimum nanosilica replacement for compressive strength of nanosilicate-crete block used in this study is 3%NS replacement by weight of cement for all mix ratios. Also, the compressive strengths values after 7 days curing are in conformity with specifications from codes. Based on the results obtained, it was recommended that for the production of nanosilicate-crete hollow block with a high compressive strength, nanosilica produced from rice husk ash should replace ordinary Portland cement by 3% of weight of cement.