Considering 105 ZnO polymorphs we use many body GW and density functional based calculations to probe how the band gap is affected by nanoporosity. Within a reasonable range of energetic stability, we predict that nanoporosity can induce band gap increases of up to ∼1.5 eV relative to wurtzite ZnO. Our results further imply that structural stability and band gap increase are fundamentally linked to pore system dimensionality. We suggest that nanoporosity could be employed as a general band gap engineering method for morphologically and electronically tailored functional materials.