Pores in a solid can effectively reduce thermal conduction, but they are not favored in thermoelectric materials due to simultaneous deterioration of electrical conductivity. Conceivably, creating a porous structure may endow thermoelectric performance enhancement provided that overwhelming reduction of electrical conductivity can be suppressed. This work demonstrates such an example, in which a porous structure is formed leading to a significant enhancement in the thermoelectric figure of merit (zT). By a unique BiI3 sublimation technique, pore networks can be introduced into tetrahedrite Cu12Sb4S13‐based materials, accompanied by changes in their hierarchical structures. The addition of a small quantity of BiI3 (0.7 vol%) results in a ≈72% reduction in the lattice thermal conductivity, whereas the electrical conductivity is improved due to unexpected enhanced carrier mobility. As a result, an enhanced zT of 1.15 at 723 K in porous tetrahedrite and a high conversion efficiency of 6% at ΔT = 419 K in a fabricated segmented single‐leg based on this porous material are achieved. This work offers an effective way to concurrently modulate the electrical and thermal properties during the synthesis of high‐performance porous thermoelectric materials. A porous network structure with excellent electrical properties can enhance the thermoelectric performance of solid materials. This work demonstrates that a porous structure can be introduced into tetrahedrite‐based synthetic minerals by a unique BiI3 sublimation technique. The multiscale architectures simultaneously disrupt phonon transport and trigger energy‐dependent scattering of holes, leading to a superior zT value of 1.15 at 723 K.