We have applied the surface-sensitive nonlinear optical technique of magnetization-induced second harmonic generation (MSHG) to plasmonic, magnetic nanostructures made of Ni. We show that surface plasmon contributions to the MSHG signal can reveal the direction of the magnetization. Both the plasmonic and the magnetic nonlinear optical responses can be tuned; our results indicate novel ways to combine nanophotonics, nanoelectronics, and nanomagnetics and suggest the possibility for large magneto-chiral effects in metamaterials.