The advent of metal halide perovskites and their extraordinary optoelectronic properties have revolutionized the field of light-emitting diodes. These materials are celebrated for their ease of processing, tunable bandgaps, high luminescence efficiency, and narrow emission linewidths, positioning perovskite light-emitting diodes (PeLEDs) as promising alternatives for display and lighting technologies. In less than a decade, PeLEDs have achieved external quantum efficiencies (EQEs) exceeding 25% for green and red emissions. Additionally, blue PeLEDs, which demand larger bandgap semiconductors, are on the cusp of achieving EQEs greater than 20%. Substantial progress has also been made in developing novel materials with wider bandgaps, facilitating the transition towards deep blue and violet emission. Jin et al. reported using the 2D perovskite 2-phenylethylammonium (C6H5CH2CH2NH3 + , PEA) lead bromide (PEA2PbBr4) to achieve color-pure violet LEDs with 0.04% EQEs. By adapting electric-field-deposition techniques, Jie et al. achieved deep blue LEDs with 0.31% EQEs. Besides 2D perovskites, 3D perovskite nanocrystals have also been explored for deep blue and violet devices. By synthesizing CsPbCl3 nanocrystals with phenylphosphonic dichloride (PhPOCl2), Qi et al. developed bright and stable CsPbCl3 nanocrystals and fabricated violet LEDs with peak emission at 405 nm and 0.18% EQEs. Regarding lead-free perovskites, Shan et al. synthesized Cs3Sb2Br9 quantum dots and achieved violet LEDs with 0.21% EQEs. Previously, our group improved the 2D perovskite crystallization process and produced violet LEDs with EQEs of 0.41% at 408 nm. Despite this progress, solution processed PeLEDs that can efficiently emit in the UV region has remained a challenging goal. The endeavor towards UV PeLEDs imposes even stricter requirements for larger bandgaps in perovskite emitting materials and poses heightened challenges in the design of charge transport layers and the management of radiative recombination and energy transfer. In this work, we present PeLEDs based on a 2D perovskite, which achieves a single electroluminescence (EL) peak below 400 nm with a peak EQE of 0.16%. This effort not only validates the feasibility of UV perovskite LEDs but also provides device design rules to ensure color-pure and efficient perovskite light emission.