Researchers are continuously investigating new sustainable alternatives to cement to reduce the harmful environmental impacts of the concrete industry. Particularly, the studies mainly focus on the effect of fully or partially replacing cement with recycled or different types of materials on the mechanical properties of concrete. Out of the various materials investigated, the inclusion of micro silica (MS) and nano silica (NS) to partially replace cement has shown promising results. However, more research is still required to determine the suitable quantity of MS and NS in the concrete mix without adversely affecting its strength. Therefore, this research aims at studying the effect of partially replacing cement with MS and NS to enhance the strength and workability of concrete. The influence of different percentages of MS and NS in the concrete mix was investigated. Two types of tests were performed on five concrete mixes to find the optimum concrete mix including slump tests and compressive strength tests. Test results showed that the addition of NS was beneficial in terms of improving the workability of the concrete mix. In fact, the highest enhancement in the slump value was in the mix that had 8% MS and 2% NS with 28% increase compared to the control mix, followed by 9% MS and 1% NS mix with 26% increase. In addition, using 9% of MS and 1% of NS provided the highest enhancement in the compressive strength with 40.7% improvement compared to the control mix. Therefore, based on the results of this study, it is recommended to partially replace cement with 9% MS and 1% NS to improve the overall performance of concrete.