Organic–inorganic halide perovskites are efficient absorbers for solar cells. Nevertheless, the trap states at the surfaces and grain boundaries are a detrimental factor compromising the device performance. Here, an organic dye (AQ310) is employed as passivator to reduce the trap states of the perovskites and promote better stability. The results demonstrate that the trap states of perovskite are minimized by the presence of AQ310's COOH group and the formation of coordination with under‐coordinated Pb2+ ions. The resulting carrier recombination time is prolonged and verified by the photoluminescence and open‐circuit voltage decay measurements. Consequently, the best average power conversion efficiency (PCE) of 19.43% is achieved for the perovskite solar cell (PSC) with AQ310 passivation, as compared with a low average PCE of 17.98% for the PSC without AQ310 passivation. An organic dye (AQ310) with COOH functional group as passivator reduces the trap states of the perovskites and promotes better stability. An average efficiency of 19.43% for the AQ310‐passivated device is achieved as compared with a low average efficiency of 17.98% for the device without AQ310 passivation.