Converting CO2into energy-rich fuels by using solar energy is a sustainable solution that promotes a carbon-neutral economy and mitigates our reliance on fossil fuels. However, affordable and efficient CO2conversion remains an ongoing challenge. Here, we introduce polymeric g-C3N4into the pores of a hollow In2O3microtube. This architecture results in a compact and staggered arrangement between g-C3N4and In2O3components with an increased contact interface for improved charge separation. The hollow interior further contributes to strengthening light absorption. The resulting g-C3N4-In2O3hollow tubes exhibit superior activity (274 μmol·g–1·h–1) toward CO2to CO conversion in comparison with those of pure In2O3and g-C3N4(5.5 and 93.6 μmol·g–1·h–1, respectively), underlining the role of integrating g-C3N4and In2O3in this advanced system. This work offers a strategy for the advanced design and preparation of hollow heterostructures for optimizing CO2adsorption and conversion by integrating inorganic and organic semiconductors.