This study investigates the influence of selected nanomaterials — primarily nano-silica (nSiO₂), carbon nanotubes (CNT), and graphene oxide (GO) — on the compressive strength, water absorption, and carbonation resistance of ordinary Portland cement (OPC) concrete. Specimens incorporating nanomaterial dosages between 0.03% and 3% by cement weight were cast, cured, and tested at 7, 28, and 90 days. Results demonstrate that a 3% nano-silica addition yields a 37.7% improvement in 28-day compressive strength over the control, while a hybrid NS + CNT blend achieves 52.6% gain. Microstructural examination via SEM and XRD confirms pore refinement and enhanced interfacial transition zone (ITZ) density. Findings affirm nanotechnology as a viable strategy for next-generation high-performance concrete.