Recently, bioinspired fluorescent materials have drawn ever-increasing attention due to their ecofriendliness and easy accessibility. Herein, we demonstrate that anthraquinone/metal ion coordination complexes can form well-defined crystals and possess obvious fluorescence enhancement properties. The fluorescence quantum yields of anthraquinone/metal ion assemblies are more than 2 orders of magnitude compared to those of anthraquinone assemblies. The electronic structures of the first excited singlet states of anthraquinone/metal ion molecules are obtained, and the mechanism of the fluorescence enhancement is elucidated. Such photoluminescent anthraquinone/metal ion crystals can be considered as efficient phosphors in fabricating light-emitting diodes. This work provides a simple route for the development of highly efficient natural fluorescent materials.