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Herein, two new iridium(III) complexes, namely <b>Ir2</b> and <b>Ir3</b>, with a phenyl or triphenylamine (TPA) moiety at the 4-position of the phenyl ring at 2-phenylbenzothiazole, have been synthesized, and their emission properties have been studied systematically compared with the non-substituted complex <b>Ir1</b>. These three complexes exhibit aggregation-induced emission (AIE) in H₂O/CH₃CN. The TPA-substituted complex <b>Ir3</b> shows the highest AIE activity. All complexes can be used as sensors to detect picric acid (PA) in water. The Stern–Volmer constant (<i>K</i>_SV) of <b>Ir3</b> for the detection of PA was determined to be 1.96 × 10⁶ M⁻¹, with a low limit of detection of 2.52 nM. Proton nuclear magnetic resonance spectra, high-resolution mass spectrometry analysis, and density function theory calculations confirm that the emission quenching mechanism of <b>Ir3</b> is caused by photo-induced electron transfer. Furthermore, the efficient detection of PA in natural water proves that <b>Ir1</b>–<b>Ir3</b> can be used as promising sensors in the natural environment. These results suggest that the AIE-active iridium(III) complexes can be used to detect PA under environment-friendly conditions.