Different kinds of electrospun products were designed and fabricated for diverse applications. This chapter reviews the recent progress of functionalization strategies for nanofibers. Semiconductor nanoparticles, due to their attractive photonic, electronic, magnetic, and chemical properties, are also of interest in functionalizing electrospun polymer products. In order to improve the dispersion of semiconductor nanoparticles, stabilizers based on organic small molecules or polymers were often applied. Many metal or semiconductor nanocomponents were successfully incorporated into polymeric fibers by direct-dispersed electrospinning for obtaining functional materials, including both in situ and ex situ processes. In some literature, the in situ direct-dispersed process was also named as sol-gel method. Carbon nanomaterials were often incorporated into electrospun polymer fiber matrix, besides metal and semiconductor nanocomponents. Carbon nanotubes are functionalized before being incorporated in fibers, by means of small molecules (sodium dodecyl sulfate), highly branched polymers, or some other surface chemical functionalization methods.