Ruddlesden–Popper perovskite, (PEA)2PbBr4 (PEA = C8H9NH3), is a steady and inexpensive material with a broad bandgap and a narrow‐band emission. These features make it a potential candidate for deep‐blue light‐emitting diodes (LEDs). However, due to the weak exciton binding energy, LEDs based on the perovskite thin films usually possess a very low external quantum efficiency (EQE) of <0.03%. Here, for the first time, the construction of high‐performance deep‐blue LEDs based on 2D (PEA)2PbBr4 nanoplates (NPs) is demonstrated. The as‐fabricated (PEA)2PbBr4 NPs film shows a deep‐blue emission at 410 nm with excellent stability under ambient conditions. Impressively, LEDs based on the (PEA)2PbBr4 NPs film deliver a bright deep‐blue emission with a maximum luminance of 147.6 cd m−2 and a high EQE up to 0.31%, which represents the most efficient and brightest perovskite LEDs operating at deep‐blue wavelengths. Furthermore, the LEDs retain over 80% of their efficiencies for over 1350 min under ≈60% relative humidity. The steady and bright deep‐blue LEDs can be used as an excitation light source to realize white light emission, which shows the potential for light communication. The work provides scope for developing perovskite into efficient and deep‐blue LEDs for low‐cost light source and light communication.