We have demonstrated a fabrication procedure for spin-electronic devices by using two-dimentional titania nanosheets. Magneto-optical Kerr measurements demonstrate that Co-substituted titania nanosheets (Ti0.8Co0.2O2) act as nanoscale ferromagnetic layers at room temperature, and their multilayer-assemblies exhibit robust magnetic circular dichroism (104–105 deg/cm) near the absorption edge at 260 nm, an operating wavelength being the shortest attained so far. The availability of ferromagnetic nanostructures and their molecule-level assembly allow the rational design and construction of high-efficiency magneto-optical devices by forming superlattices.