Target-specific drug delivery system that can transport an effective dosage of anti-cancer drugs to the targeted tumor cells can significantly reduce drug toxicity to the normal cells and increase the therapeutic effect of the drug. In our work, we have evaluated the cytotoxic potential of paclitaxel-loaded silica nanoparticles (Si-PTX NPs) prepared by template-directed stober synthesis technique. The particles were characterized using transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. We have modified the surface of the drug-loaded particles chemically and conjugated a tumor-specific aptamer (Apt-Si-PTX NPs) to facilitate targeted drug delivery to the cancer cells. In vitro studies carried out demonstrated that the aptamer-conjugated paclitaxel-loaded silica nanoparticles could target the cancer cells with high specificity and destroy them effectively, while sparing the normal cells. This work concludes that the aptamer-tagged paclitaxel-loaded silica nanoparticles are excellent targeting moieties for targeted drug delivery to tumor cells.