Despite the rapid advances of red and green perovskite light-emitting diodes (PeLEDs), achieving high brightness with high external quantum efficiency (EQE) remains a challenge for the pure-blue PeLEDs, which greatly hinders their practical applications, such as white-light illumination and in optical communication as a high-speed and low-loss light source. Herein, we report a high-performance pure-blue PeLED based on mixed-halide quasi-2D perovskites incorporated with a zwitterionic molecule of 3-(benzyldimethylammonio) propanesulfonate (3-BAS). Experimental and density functional theory analysis reveals that 3-BAS can simultaneously eliminate non-radiative recombination loss, suppress halide migration, and regulate phase distribution for smoothing energy transfer in the mixed-halide quasi-2D perovskites, leading to the final perovskites with high photoluminescence quantum yield and robust spectrum stability. Thus, the high-performance pure-blue PeLED with a recorded brightness with 1806 cd m ^{- 2} and a relative higher EQE of 9.25% is achieved, which is successfully demonstrated in a visible light communication system for voice signal transmission. We pave the way for achieving highly efficient pure-blue PeLEDs with great application potential in future optical communication networks.