Luminescent properties of Eu³⁺ activated double perovskite structure Ca₃WO₆ were investigated. It emits an ideal red color centered at the wavelength of 618 nm with suitable excitation from f–f transitions of Eu³⁺ ions (360–550 nm) matching the near ultraviolet and blue LEDs. Charge compensation effect of Li⁺, Na⁺, and K⁺ was investigated, and K⁺ proved to be the best. The co-doping ion K⁺ has a great effect on the lattice distortion of the host matrix Ca₃WO₆, which facilitates the red emission of Eu³⁺. The substitution site for Ca in Ca₃WO₆ was analyzed in detail by Raman spectra and calculation results. A-site substitution is responsible for the red emission of Eu³⁺ activated Ca₃WO₆. The integrated emission intensity of optimal Ca₃WO₆:K⁺,Eu³⁺ excited at 395 nm is about 3.5 times greater than that of Y₂O₂S:Eu³⁺ commercial phosphors, which makes it a promising red phosphor for white LEDs.