Even though the production of nanoparticles of silver and gold dates back many centuries, characterization and manipulation at nanoscale has initiated a new era for nanotechnology. Spreading its wings beyond physics and materials science, its scope of application in molecular biology, biochemistry, and medicine is only recently being appreciated. This necessitated a need for the interaction between nanoparticles and biomolecules. The importance of this field can be supported by the dedication of fifth issue of JACS Select that contains 22 communications and articles related to chemistry at the Nano–Bio Interface. The designing of various nanoparticles for biological applications has been enabled by advances in synthesis of functionalized nanoparticles that makes them compatible with biomolecules. In wet-chemical process the nanoparticles preparation is carried out in the presence of biomolecules like glucose, soluble starch, or chitosan that leads to stabilization of nanoparticles. Another approach is based on linker where the biomolecules like DNA, proteins are immobilized on nanoparticles through linkers like citrate, streptavidin, etc. Many of the free aminoacids were also used to stabilize fluorescence nanoparticles like cadmium sulfide and zinc sulfide. The recognition capability of biomolecules also helped in directed synthesis of nanoparticles with desired morphology and arrangement. In addition, biomolecules support in biotemplating and biomimetic synthesis of nanomaterials. Both the biomolecules and nanoparticles meet at the same nanometer scale that makes their interaction very interesting and promising in various applications. This chapter covers the major processes/products where biomolecules meet nanoparticles and their chemical interaction.