Nanotechnology is a relatively new field of science and technology that studies tiny objects (0.1–100 nm). Due to various positive attributes displayed by the biogenic synthesis of nanoparticles (NPs) such as cost-effectiveness, none to negligible environmental hazards, and biological reduction served as an attractive alternative to its counterpart chemical methods. Along with the impartial and thorough overview of the current understanding of NPs uptake into the mammalian cells and underlying factors governing nano-cellular interactions, this report also outlines the properties and therapeutic applications of NPs. This study elaborated on the use of nanotechnology in medicine, health, electronics, and the environment. This manuscript briefly discusses NPs in medication delivery, cancer therapy, protein, and peptide delivery.