A unique carbon-confined metal oxide cube-in-tube nanostructure is synthesized by a facile precursor-modified electrospinning method with subsequent pyrolysis. This nanostructure has a partly graphitized carbon layer with manganese oxide nanoparticles embedded as the tube and amorphous CoSnO3 hollow cubes uniformly distributed inside the tube. As a lithium-ion battery anode, this architecture exhibits a high reversible discharge capacity and rate capability.