Highly efficient cyan‐emitting phosphor materials are indispensable for closing the cyan gap in spectra of the traditional phosphor‐converted white light‐emitting diodes (WLEDs) to achieve high‐quality full‐spectrum white lighting. In this work, bright cyan‐emitting Ca 3 Ga 4 O 9 (CGO):0.02Bi 3+ ,0.07Zn 2+ phosphor is developed to bridge the cyan gap. Such a Bi 3+ ,Zn 2+ codoping enhances the cyan emission of CGO:0.02Bi 3+ by 4.1 times due to the influence of morphology and size of phosphor particles, charge compensation and lattice distortion. Interestingly, codoping La 3+ ions into the current system can achieve a photoluminescence tuning of CGO:0.02Bi 3+ from cyan to yellowish‐green by crystallographic site engineering. Besides, Bi 3+ –Eu 3+ energy transfer is successfully realized in CGO:0.02Bi 3+ ,0.07Zn 2+ , n Eu 3+ phosphors and the emission color tuning from cyan to orange is observed. The investigation of thermal quenching behaviors reveals that the incorporation of Zn 2+ and La 3+ improves the thermal stability of CGO:0.02Bi 3+ . Finally, CGO:0.02Bi 3+ ,0.07Zn 2+ ,0.10Eu 3+ phosphor is employed to obtain a single‐phased warm WLED device. A full‐spectrum WLED device with remarkable color rendering index (Ra) of 97.4 and high luminous efficiency of 69.72 lm W −1 is generated by utilizing CGO:0.02Bi 3+ ,0.07Zn 2+ phosphor. This result suggests the important effect of CGO:0.02Bi 3+ ,0.07Zn 2+ phosphor on closing the cyan gap, providing new insights of cyan‐emitting phosphors applied in full‐spectrum white lighting.