Er3+‐doped CaF2 transparent ceramics are promising mid‐infrared gain materials because of their utra‐low phonon energy as well as excellent physical, chemical, and optical properties. However, existing hot‐pressed and hot‐formed CaF2 ceramics are very difficult to be used in practical applications due to residual pores and weak polycrystallization, respectively. Here, we developed the high quality Er3+‐doped CaF2 transparent polycrystalline ceramic by single crystal ceramization. The sample exhibits obvious polycrystalline structure, good mechanical properties, perfectly transmittance, and excellent mid‐infrared performance, which provides significant and wide‐ranging opportunities for advanced mid‐infrared gain materials.