Series of Ce3+‐activated Sr4La6(SiO4)6Cl2 (SLSOC) cyan‐emitting phosphors are designed to satisfy the demands of plant growth and full‐spectrum white‐light diode (white‐LED). Herein, to modify the luminescence behaviors of phosphors, Ce3+ is designed to occupy the different sites in SLSOC host lattices. Excited at 353 nm, the resultant phosphors emit glaring cyan emission originating from Ce3+ with an asymmetric emission band, which is assigned to the two‐site occupation of Ce3+ at Sr2+ or La3+ crystallographic sites. Moreover, the quantum efficiency and thermal quenching performances of synthesized phosphors are also analyzed, which are all dependent on the crystallographic sites taken by Ce3+. Via using the designed phosphors, two cyan‐emitting LEDs are packaged and their emissions are highly overlapped with the absorption spectra of plant pigments, which allow their feasibilities in plant growth. Furthermore, the artificial plant growth experiments are performed to clarify the significant positive influence of the packaged cyan‐emitting LEDs on plant growth. Additionally, via using the prepared cyan‐emitting phosphors to compensate the cyan gap, the full‐spectrum white‐LEDs with high electroluminescence performances are designed. These achievements reveal that the Ce3+‐activated SLSOC phosphors with controllable luminescence properties are promising cyan‐emitting converters for artificial plant growth LED and full‐spectrum white‐LED.