Due to their excellent optical properties, all-inorganic halide perovskite nanocrystals (NCs) show great potential in lighting applications. However, the poor stability in a humid environment and strong ion exchange characteristics hinder the practical application of the exciting material in optoelectronic devices. In this work, we demonstrate the use of anthracene-coated CsCu2I3 (CsCu2I3@anthracene) NCs as efficient and stable color conversion phosphors in white light-emitting diodes (WLEDs). Synthesized via a facile solution process, the composite exhibits a high photoluminescence quantum yield of 27.3%. The efficient luminescence is enabled by the anthracene coating, which not only produces strong blue emission but also shields the yellow-emitting CsCu2I3 NCs from moisture and water. In addition, anthracene has minimal interactions with CsCu2I3 both chemically and optically. Therefore, by simple tailoring the mass ratio of the two components, one can easily combine the broad blue and yellow emissions to achieve white light with different correlated color temperatures (CCT) and long-term color stability. As a proof of concept, a WLED with a high color rendering index of 83, color coordinate of (0.31, 0.31), and CCT of 6718 K was obtained by combining CsCu2I3@anthracene with UV LED chips. Moreover, the fabricated WLED exhibits excellent color stability with operation voltage and time, attesting to the superior water resistance capability of the organic coating. The strategy proposed here can potentially further promote the application of lead-free inorganic perovskite NCs in the field of white light illumination.