We have successfully fabricated hierarchical ZnSnO3 nanocages via a facile one-pot solution synthesis method. Field emission scanning electron microscopic and transmission electron microscopic results reveal that the cubic ZnSnO3 samples with hollow interior and porous shells are cage-like structure with the side length of 200−400 nm, where the subunits are irregular-shaped nanoparticles. The time-dependent morphology of the ZnSnO3 samples has been investigated, and a possible formation mechanism of these hierarchical structures is proposed. Moreover, gas sensor based on hierarchical ZnSnO3 nanocages exhibits better sensing properties compared with the solid ZnSnO3 nanocubes. The facile preparation method may provide an easy path to the extendable synthesis of other functional nanomaterials with hollow structure and further exploitation of the potential applications.