In modern-day medicine, nanoparticles and nanocarriers are rapidly evolving fields in therapeutics and are the building blocks of nanomedicine, which emphasize the use of nanoscale particles that have a wide array of functions from working as a diagnostic tool to the screening, monitoring, and controlling of various diseases to the delivery of drugs at specific targets in a controlled manner. With the advancement in technologies, it is proven that nanoparticles have a greater potential in wide biomedical applications. Due to their ability to bind with both hydrophobic and lyophilic substances, lower particle size, higher carrier capacity, nanoparticles serve as a favorable platform for specific and targeted drug delivery in disease treatment. Nanoformulations can improve the safety, pharmacokinetic characteristics, and bioavailability of administered drugs, and can improve the therapeutic effect when compared with conventional therapies. Besides, nanoparticles may also be effective in delivering nucleotides, vaccines, and recombinant proteins. Several varieties of nanoparticles are available: different metal and polymeric nanoparticles like gold/silver nanoparticles and micelles, dendrimers. Carbon-derived nanoparticles like quantum dots, carbon tubes, and many other nano assemblies. Numerous nanocarriers, nanoparticle-based drug delivery systems, and drug targeting systems are either developed or under development. In this chapter, we will emphasize mainly the specific and targeted nanoparticles and the use of various nanocarriers for the targeted delivery of drugs in various diseases. The opportunities and challenges of using nanoparticles/nanocarriers in targeted delivery along with its clinical applications are also discussed here.