A color-tunable BaCa2MgSi2O8:Eu2+, Mn2+ phosphor (BCMSO:Eu, Mn) was synthesized by a solid state reaction. The BCMSO:Eu exhibits blue emission and broad excitation bands corresponding to the allowed f → d electronic transition of Eu2+, which can match well with ultraviolet (UV) light emitting diode (LED) chips. Via efficient energy transfer from Eu2+ to Mn2+, the emission hue can be tuned by tuning the Eu2+/Mn2+ ratio, with the emission hue of BCMSO:Eu, Mn varying from blue to white light, and eventually to red. Meanwhile, high-quality white-emitting light can be generated using an optimized composition of BCMSO:1%Eu2+, 20%Mn2+ with CIE coordinates of (0.3384, 0.2176) and CRI of 82, which is superior to that of blue chip and YAG phosphors. The results indicate that as-synthesized BCMSO:Eu2+, Mn2+ phosphors have potential as single-phased and UV excitable white-emitting phosphors.