Self-assembled vertical nanostructures take advantage of high interface-to-volume ratio and can be used to design new functionalities by the choice of a proper combination of constituents. However, most of the studies to date have emphasized the functional controllability of the nanostructures using external electric or magnetic fields. In this study, to introduce light (or photons) as an external control parameter in a self-assembled nanostructure system, we have successfully synthesized oxide nanostructures with CoFe 2O 4 nanopillars embedded in a SrRuO 3 matrix. The combination of photostrictive SrRuO 3 and magnetostrictive CoFe 2O 4 in the intimately assembled nanostructures leads to a light-induced, ultrafast change in magnetization of the CoFe 2O 4 nanopillars. Our work demonstrates a novel concept on oxide nanostructure design and opens an alternative pathway for the explorations of diverse functionalities in heteroepitaxial self-assembled oxide nanostructures.