In recent years, all-inorganic perovskites have attracted considerable research attention. However, the advancement of lead-based perovskites has encountered substantial challenges, redirecting current research efforts toward lead-free alternatives. In this study, we synthesized novel Cs4MnBi2Cl12 perovskite crystals at 80 °C. Furthermore, Tb3+ ions were introduced to enhance the fluorescence properties and stability of the as-prepared perovskite crystals (PCs). The photoluminescence quantum yield (PLQY) of Tb3+-doped PCs was 25.45 % (∼598 nm), making a two-fold increase compared with the original PCs. In the PCs, [BiCl6]3− octahedrons serve as energy collectors, generating excitons, while [MnCl6]4− octahedrons function as luminescence centers of the receptor. Owing to their entirely inorganic composition, the PCs exhibited exceptional stability under sunlight and across a wide range of temperatures. Finally, we applied the PCs to fiber composite paper and an light-emitting diode (LED) device, which retained their specific stability after the modification. The findings of this study offer nover insight for incorporating perovskites into fiber applications and optoelectronic devices.