The self-assembly of peptides is a universal phenomenon in nature that has immense potential to give rise to sophisticated structures. The formation of well-ordered suprastructures in biological systems has attracted scientists over several decades to unravel its unique properties for useful applications. One of the classic essences of modern nanotechnology is the spontaneous formation of well-ordered nanostructures by the process of self-association. The process of self-assembled nanostructures can be obtained by building blocks of both organic and inorganic components. Among these organic building blocks, peptide-based nanostructures have emerged as an important source of self-assembled nanostructures, where significant efforts have been devoted by scientists to understand their sophisticated system. Several natural self-assembled peptides have inspired researchers to develop synthetic nanostructures for various noteworthy applications. Self-assembled peptides have established a wide range of formation of nanostructures such as nanorods, nanotubes, nanotapes, nanoparticles, nanosheets, vesicles, and many more. These nanostructures represent unique properties of biocompatibility, chemical diversity, high surface area, wide loading capacity of drugs, and the ability to target different recognition sites. Several critical parameters are considered for the formation of such peptide-based nanostructures before development. This process, however, has several challenges and issues, which are still persistent. The nature of the formation of self-assembled peptide nanostructures are formed under controlled conditions of kinetic and or thermodynamic assembly process. The versatility of self-assembled nanostructures has paved the way for a variety of applications in the physical, chemical, and biological including supercapacitors, catalysis, sensors, photothermal therapy, etc. This chapter focuses on the engineered self-assembled peptides-based nanostructures, design, formation, advantages, and challenges. Furthermore, the utilization of such peptide nanostructures in biomedical applications such as drug delivery, biosensors, bioimaging, antimicrobial agents, etc. that has been reported earlier are also covered in this chapter.