Nanotechnology, when this word comes in mind, it gives deep thought of new development in communication, medical science, intelligent transport system and many more. Ferrites nanoparticles have great significance owing to their amazing chemical and physical properties. In modern era we are developing materials for microwave applications and communication devices. Before the discovery of semiconductor memory chips, ferrites were the major form for electronic memory used in computers. Scientist have been studying and working with nanoparticles in magnetically guided drug delivery. The reactivity of material increases by the use of nanoparticles of that material. The dielectric characteristics of ferrites lean on diverse factors for instance methods of preparations and chemical composition. In various studies it has been found that their conductivity has dependence on temperature, composition and frequency. Among the various kinds of ferrites, Ni–Zn ferrites are viewed as the most adaptable ferrites as a result of their novel characteristics for applications at high frequency. The Ni-Zn ferrites are exploited as core materials in a variety of EM devices as well as have broad range of industrial applications e.g. inductors, microwave devices, power supplies, high and low frequency transformer cores, electromagnetic interference (EMI) suppressions and antenna rods. These broad ranges of applications are owing to their high resistivity, low eddy currents, high saturation magnetization, chemical stability and high Curie temperature. In view of this, the present chapter deals with the research progress on nickel-zinc ferrites in the bulk as well as nano size.