Over the past couple of decades, nanocrystalline materials, commonly noted as nanomaterials, are receiving wide attention among scientists due to unusual material properties at the nanoscale that are not foreseen in the micro-/macroscale. This field of nanomaterials is still very young, requires a long quest, and upholds prospects beyond imagination. With this in view, this chapter compiles the advancements of magnetic behaviors of such nanomaterials. Starting from the origin of magnetism in nanomaterials, we have systematically addressed their functionality, fabrication, and characteristics. This chapter ends with concluding remarks and the future prospects of magnetic nanomaterials.