Zero‐dimensional (0D) structured lead‐free metal halides have recently attracted widespread attention due to their high photoluminescence quantum yield (PLQY) and negligible self‐absorption, showing enormous potential as optical waveguides towards miniaturized photonic devices. However, due to the great difficulty in growth of rod‐like nano/micro‐sized morphologies, such applications have been less explored. Herein, a new‐type emissive organic‐inorganic manganese (II) halide crystal (TPS2MnCl4, TPS = C18H15S, triphenylsulfonium) in the form of microrods is synthesized via a facile chloride ion (Cl‐) induced oriented growth method. Due to a combination of attractive features such as a high PLQY of 86%, negligible self‐absorption and smooth crystal surface, TPS2MnCl4 microrods are well suited for use in optical waveguide with an ultra‐low optical loss coefficient of 1.20·10‐4 dB μm‐1, superior to that of most organic‐inorganic metal halide hybrids, organic materials, polymers and metal nanoclusters to the best of our knowledge. Importantly, TPS2MnCl4 microrods can further work as dual‐mode optical waveguides, combining active and passive light transmission functionalities in one single crystal. In addition, TPS2MnCl4 microrods also display remarkable performance in lighting and anti‐counterfeiting due to their distinct optical properties and commendable stability.