Traditional chemical drugs used for treatment have demonstrated many adverse effects, which may harm healthy organs besides their efficiency. Therefore, the main aim of the systems of drug delivery is to maximize the efficacy of the drugs by targeting the abnormal cells to deliver the maximum dose for them and reduce the possible side effects. Recently, the trends to develop drug delivery systems have increased in various fields such as the biomedical, pharmaceutical industries, and nanomedicine. Despite the significant improvement of material properties in the nanoscale, some drawbacks still restrict their applications. Nanofillers are fillers with particle sizes ranging from 1 to 100 nm that possess unique properties (electrical, chemical, optical, and mechanical) that enhance the drug release profile. Using nanofillers gives the power to achieve the treatment requirements perfectly with high control of drug dose release, besides avoiding biological barriers. There are increasing efforts to understand the fundamental interactions and structure-properties relationships that arise from these new forms and avoid their toxicities. This chapter will discuss how nanofillers enhance composites’ properties and functionalities. We will focus on the nanofillers used in drug delivery systems as nanofiller-enhanced capsules.