Herein, an Ir(III) complex-doped coordination polymer network (Ir(III)@GMP–Eu³⁺) is fabricated for the first time for the ratiometric luminescent detection of the anthrax biomarker 2,6-dipicolinic acid (DPA) through the analysis of time-resolved emission spectra (TRES). The linear detection range is from 10 nM to 5 μM with a detection limit of 3.3 nM in aqueous solution. Attributed to the long lifetime of Ir(III)@GMP–Eu³⁺, the developed sensor exhibits an excellent DPA monitoring ability in a high-background solution through TRES.