Nanofillers are a type of drug delivery system that utilizes nanoparticles as a method of transporting medications to specific regions within the body. These nanoparticles, also known as “nanocarriers,” are designed to encapsulate drugs and protect them from degradation while in transit to the site of action. The use of nanocarriers can enhance the pharmacokinetics and pharmacodynamics of drugs, increasing their bioavailability and targeting specific cells or tissues. Overall, nanofillers have the potential to improve the efficacy and safety of drug delivery, making them a promising area of research in the field of pharmaceuticals. Additionally, nanocarriers can be engineered to target specific cells or tissues, increasing the specificity of drug delivery. This can be accomplished using various approaches such as incorporating targeting moieties on the surface of the nanocarrier, designing the nanocarrier to mimic the structure of specific receptors or ligands, or physically directing the nanocarrier to the target site using external factors like pH, temperature, or magnetic fields. Compared to traditional drug delivery methods, targeted delivery offers the potential for enhanced therapeutic efficacy and minimized side effects. Nonetheless, it is crucial to acknowledge that nanocarriers present their own array of hurdles that require attention, including toxicity, stability, and regulatory concerns. This chapter highlights various nanofillers used in drug delivery, factors that enhance their effectiveness, and the underlying mechanisms of drug delivery using these carriers. Additionally, this chapter encompasses a comprehensive review of the recent advancements in nanofiller-based drug delivery.