We have studied structural, electronic, and magnetic properties of Ni n M (M=Hf, Ta, W) clusters with n=1–12 using spin density functional theory. The calculated results find that a single impurity M (M=Hf, Ta, W) enhances the binding energy of the nickel cluster, reduces their magnetic moment and decreases the ionization potential. Hf and Ta occupies the substitutional vertex site accompanied with substantial distortion in the nickel clusters. We find that the geometries of the host clusters do not change significantly after the doping of the W atom. After n>8, W atom prefers the interstitial site in the host cluster. The ability to delocalize the Ni-3d electrons decreases from Hf to W. The magnetic moments of doped clusters (Ni n Hf, Ni n Ta and Ni n W) are quenched because of the antiferromagnetic arrangement of the M (Hf, Ta, W) electrons.