In this work, high-temperature crystalline α′_H- and α-Ca₂SiO₄:Eu²⁺ phosphors stabilized at room temperature are synthesized by incorporating a suitable amount of phosphorus ions. The crystalline structures and the influence of phosphorus ions on the crystalline phases as well as the photoluminescent properties for phosphorus stabilized α′_H- and α-Ca₂SiO₄:Eu²⁺ phosphors are investigated in detail. The results indicate that the α′_H- and α-Ca₂SiO₄ high-temperature crystalline phases can be quenched at room temperature with incorporation of 12% and 42% phosphorus ions (replacing Si ions), respectively, shielding the stability effect of Eu²⁺ ions on the β-form (low Eu²⁺ concentration) and α′_L-form (high Eu²⁺ concentration). Tunable emissions from green to orange-red light are observed with the increase of the Eu²⁺ doping concentration in both of α′_H-Ca₂Si_0.88P_0.12O₄:Eu²⁺ and α-Ca₂Si_0.58P_0.42O₄:Eu²⁺ phosphors, indicating their promising prospect in applications of LED lighting.