In the present work, a series of Eu²⁺ activated Ca₃Al₂O₆ down-conversion phosphors have been successfully prepared via solid-state reaction method at 800 °C. Under 334 nm excitation, PL emission spectra shows broad band emission with the peak centred at 445 nm. This broad band emission is assigned to the allowed 4f⁶5d¹ → 4f⁷ electronic transition of Eu²⁺ ions. The highest emission intensity was observed for Ca₃Al₂O₆: 0.5 mol%Eu²⁺ phosphor. The CIE chromaticity diagram shows high colour purity and excellent chromaticity coordinates. This CIE diagram reveals (0.2127, 0.1102) chromaticity coordinates in the blue region with 84.21% colour purity. Further, the electron-vibrational interaction parameters such as Stokes shift, Huang-Rhys factor, effective phonon energy, zero phonon line position, and red shift have been calculated using a spectrum fitting method. These results indicate that the Eu²⁺ activated Ca₃Al₂O₆ down-conversion phosphor has great potential in the field of white LEDs.