A series of Mn4+-activated CaAl2 O4 (CAO) compounds were synthesized by co-precipitation to seek a candidate for a red-emitting phosphor to be employed in a white LED. The crystal structure, morphology, and fluorescence properties of the as-obtained phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL). The deep red luminescence of Mn4+ in CaAl2 O4 is reported and discussed. The excitation spectrum exhibited broadband emission between 260 and 550 nm with three peaks dominating at 320 nm due to the transition of 4 A2 4 T1 . The emission spectra between 600 to 720 nm displays an overwhelming emission peak at 654 nm owing to the 2 E4 A2 transition of Mn4+ ion. This research demonstrates the great promise of CaAl2 O4 :Mn4+ as a commercial red phosphor in warm white LEDs and opens up new avenues for the exploration of novel non-rare-earth red-emitting phosphors.