Nanostructured Ni-doped skutterudites Co(1-x)Ni(x)Sb3 (with x ranging from 0.01 to 0.09) were prepared by ball milling and direct-current induced hot press. It was found that the thermal conductivity was reduced due to strong electron-phonon scattering from Ni-doping as well as phonon scattering from the increased grain boundary of the nanostructures. A maximum dimensionless figure-of-merit of 0.7 was obtained in Co0.91Ni0.09Sb3 at 525 degrees C.