Perovskite light-emitting diodes (PeLEDs) hold notable promise for next-generation full-colour displays. However, realizing full-colour active-matrix displays remains a critical challenge due to varying efficiency across the red, green and blue primary colours and incompatibility with high-resolution patterning techniques. In this context, white PeLEDs paired with colour filters may offer a simplified and efficient alternative to full-colour displays. Here we demonstrate ligand-engineered CsEuI3 nanocrystals (NCs) that enable efficient single-component white electroluminescence (EL) for full-colour displays. In CsEuI3@mCP (mCP: 1,3-bis(N-carbazolyl)benzene) NCs, the intrinsic CsEuI3 inorganic field preserves blue emission from Eu2+, while surface ligand interactions modify the local Eu2+ environment and introduce complementary long-wavelength emission, producing white emission with a high colour rendering index of 85.7 and near-ideal CIE chromaticity of (0.33, 0.34). Beyond spectral modulation, mCP also promotes the electrical activation of Eu2+ emissive centres and ligand-assisted excitation involving singlet- and triplet-related states. When implementing CsEuI3@mCP NCs as the emitter, we showcase single-component white EL with a peak external quantum efficiency of 8.3% and a maximum luminance of 8,941 cd m−2. As a proof of concept, we monolithically integrate these white PeLEDs on a 256 × 256 active-matrix display chip, demonstrating dynamic video and full-colour images with a 124% NTSC colour...