Perovskite quantum dots (QDs), particularly those composed of lead halide, are considered exceptional candidates for efficient visible light communications owing to their outstanding photophysical properties. However, their striking potential is greatly constrained by their instability, posing significant challenges to their wide-ranging applications. Here, we successfully synthesized Tb-doped CsPbI3 glasses with superior structural and humidity stabilities as well as enhanced photoluminescence quantum yield (PLQY). Additionally, density functional theory calculations showed that the Tb3+ dopant tended to occupy Pb sites, enriching the excited electron density at the band edge to enhance the photoluminescence. More importantly, the Tb-doped CsPbI3 perovskite glass exhibited a high and stable net data rate of 521 Mb/s, which was higher than those of the most well-established color-converting phosphors commonly used for optical wireless communication. Our study provides an effective strategy for developing ultrastable and efficient red-emitting all-inorganic perovskite glass for light-harvesting applications, including high-speed visible light communication.