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A deep understanding of the effect of the A‐site cation cross‐exchange on the hot‐carrier relaxation dynamics in perovskite quantum dots (PQDs) has profound implications on the further development of disruptive photovoltaic technologies. In this study, the hot carrier cooling kinetics of pure FAPbI₃ (FA⁺, CH(NH₂)₂⁺), MAPbI₃ (MA⁺, CH₃NH₃⁺₊), CsPbI₃ (Cs⁺, Cesium) and alloyed FA_0.5MA_0.5PbI₃, FA_0.5Cs_0.5PbI₃, and MA_0.5Cs_0.5PbI₃ QDs are investigated using ultrafast transient absorption (TA) spectroscopy. The lifetimes of the initial fast cooling stage (<1 ps) of all the organic cation‐containing PQDs are shorter than those of the CsPbI₃ QDs, as verified by the electron‐phonon coupling strength extracted from the temperature‐dependent photoluminescence spectra. The lifetimes of the slow cooling stage of the alloyed PQDs are longer under illumination greater than 1 sun, which is ascribed to the introduction …