As increasing demand for noncontact temperature sensing, the development of a high-performance optical thermometer probe is more and more urgent. In this work, an efficient dual-mode optical thermometry strategy based on the Pr 3+ /Dy 3+ energy transfer (ET) in some typical double-perovskite oxides is presented, which offers a promising way to design FIR/lifetime dual-mode optical thermometry with excellent temperature-measuring sensitivity and signal discrimination. According to this strategy, double-perovskite La 2 MgTiO 6 :Pr 3+ /Dy 3+ phosphors are successfully synthesized. On the basis of diverse thermal responses between Pr 3+ and Dy 3+ , the FIR of Pr 3+ to Dy 3+ (four FIR mode) in this material displays outstanding optical thermometry performance from 298 to 548 K. The maximum absolute and relative sensitivities (S a and S r ) of mode 1 are 0.09 and 2.357% K −1 , being better than the current optical temperature measurement materials. For the fluorescence lifetime mode, the S a-max and S r-max values reach 2.85 × s 10 −4 and 1.814% K −1 . Furthermore, the dual-mode optical thermometry mechanism was presented and studied. It also demonstrated excellent optical thermometry performance in the other Pr 3+ /Dy 3+ codoped double-perovskite oxides, such as LaMg 0.598 Nb 0.402 O 3 , NaLa(MoO 4 ) 2 , NaGd(MoO 4 ) 2 , and NaLa(WO 4 ) 2 , proving the universality of the presented strategy. This article presents an effective Pr 3+ /Dy 3+ ET pathway for developing new and highly sensitive FIR/lifetime dual-mode optical temperature sensing materials.