A conducting polyaniline-$Fe_3O_4$ nanohybrid was synthesized via click coupling of iron oxide nanoparticles and 2-ethynylaniline. Covalent functionalization of the azide-functionalized iron oxide nanoparticles and the 2-ethynylaniline was confirmed with Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy, and the coating of polyaniline on iron oxide nanoparticles was confirmed with field-emission scanning electron microscopy. The nanohybrid incorporated into a poly(vinyl alcohol) (PVA) matrix by solution casting showed excellent compatibility with the PVA. Consequently, the mechanical properties and electrical conductivities of the resultant composite films were improved remarkably. This click coupling protocol offers the possibility of completely combining the extraordinary performance of nanohybrids with PVA properties.