Efficient cyan-emitting phosphor plays an important role in the development of solid-state lighting, which is indispensable to filling the cyan gap for full-spectrum warm-white light-emitting diodes (WLEDs) with high color rendering index (CRI). Herein, a novel highly efficient broadband cyan phosphor Ce3+-doped Ca3HfAl2Si2O12 (CHASO: Ce3+) garnet compound was developed by the substitution of Lu3+-Al3+ with Ca2+-Hf4+/Si4+ in Lu3Al5O12. The crystal structure and photoluminescence (PL) properties of CHASO: Ce3+ were investigated in detail. Notably, CHASO: Ce3+ phosphor can be effectively excited by violet light (390 – 430 nm) and exhibited bright cyan emissions around 490 nm with high PL internal quantum yields of 89.2 %. Moreover, the integrated PL intensity of the phosphor at 423 K was 66.3 % of that at room temperature. Finally, by incorporating CHASO: 11 %Ce3+ with commercial blue/yellow/red phosphor onto a violet LED chip (400 nm), the prototype full-spectrum WLEDs device exhibits warm white light with high color rendering index (CRI, Ra and R9 > 90) and low correlated color temperature 3301 K. These results suggest the highly efficient phosphor CHASO: Ce3+ is promising for low-blue full-spectrum healthy lighting.