Transition metal complexes that efficiently emit from an excited state with formally triplet character are an appealing class of compounds. However, they typically suffer from severe quenching, e. g. triplet‐triplet annihilation, in aggregated phase that often hampers their use in the solid‐state. Nonetheless, an intriguing effect, namely aggregation‐induced phosphorescence enhancement, has been sometimes observed, but clear elucidation of the mechanisms underlying this phenomenon is far from trivial. Nowadays, cyclometalated IrIII emitters play a leading role due to their outstanding features. Aiming at a rationalization of the AIPE effect, an overview of the different classes of IrIII emitters displaying enhancement of the emission upon aggregation will be herein provided along with their potential applications. Their photophysical properties will be discussed jointly with their X‐ray structural analysis. IrIII complexes represent the largest family of AIPE‐active compounds to date.