In this study, a novel, to the best of our knowledge, Cr^3+-doped garnet fluorescent material (Ca_2TbScGa_2Ge_2O_12:Cr^3+, CTSGGO:Cr^3+) in high-entropy oxides has been successfully synthesized by a high-temperature solid-phase method and systematically investigated in terms of its photoluminescence (PL) and mechanoluminescence (ML) properties. The material shows broadband near-infrared emission in the 700–900?nm range when excited by 460?nm blue light, with a half-peak width of 116?nm. Additionally, it achieves NIR-visible synergistic emission in both PL and ML modes through efficient energy transfer from Tb^3+ to Cr^3+ (with a transfer efficiency of 75%). When encapsulated in PDMS, the material exhibits dual ML responses: 450–650?nm (Tb^3+) and 650–900?nm (Cr^3+) under mechanical stress. It was integrated with commercial blue LED chips and PDMS for practical applications in …