A series of emission-tunable Ce³⁺/Tb³⁺/Eu²⁺ doped Ca₂(Mg_0.75Al_0.25)(Si_1.75Al_0.25)O₇ (denoted as CMAS) phosphors have been synthesized via a high temperature solid-state reaction method. The luminescence properties, color tuning, quantum yields (QYs), energy transfer of Ce³⁺ to Tb³⁺/Eu²⁺, thermal stability, performance of LED devices and ratiometric temperature sensing application have been systematically investigated, respectively. Importantly, through the study of thermal stability, we found that Ce³⁺ and Tb³⁺ co-doped samples were suitable for WLED applications, while Ce³⁺ and Eu²⁺ co-doped samples were suitable for temperature sensing applications. Due to the energy transfer, Ce³⁺/Tb³⁺ co-doped samples had high luminous efficiency and the quantum efficiency of more than 80% could be achieved. Their emission colors can modulate from blue to green. In addition, on the basis of the evaluation of the as-fabricated white LED lamps via selecting the corresponding phosphors, the CCT can reach 4275 K and the CRI can increase to 86.8, indicating that this series of phosphors can act as potential color-tunable phosphors for possible applications in ultraviolet light based white LEDs. Importantly, it is found that the fluorescence intensity ratio of CMAS : 5%Ce³⁺,0.5%Eu²⁺ displays linear correlation with temperature in a wide range of 253–373 K with a high sensitivity of 2.49% K⁻¹, indicating that it could be a good candidate for ratiometric optical thermometry.