[en] Multiwavelength near infrared emission of Tm³⁺ in double perovskite Y₂MgTiO₆:Mn⁴⁺/Tm³⁺ (in brief YMT: Mn⁴⁺/Tm³⁺) phosphors is to easily achieve by resonance energy transfer and downshift (or downconversion) between rare earth ions and transition metal ions. In this study, we observe the multiwavelength near infrared emissions of Tm³⁺ in Mn⁴⁺-Tm³⁺ co-doped YMT phosphors synthesized by a high temperature solid-state reaction. During the resonance energy transfer from Mn⁴⁺ to Tm³⁺, the YMT:Mn⁴⁺/Tm³⁺ phosphor exhibits three wavelength near-infrared emission around 800, 1488 and 1800 nm originating in ³H₄→³H₆, ³H₄→³F₄ and ³F₄→³H₆ of Tm³⁺ with a wide excitation band extending from 250 to 550 nm. The cascade emission of two wavelengths (1488 and 1800 nm) is mainly contributed to downconversion of Tm³⁺ ions. Based on Dexter's theory, the energy transfer mechanism is mainly contributed to a dipole-dipole interaction between Mn⁴⁺ and Tm³⁺ ions, which is responsible for the largely enhanced multiwavelength near infrared emission of Tm³⁺. Multiwavelength near infrared emission of Tm³⁺ make them potential application in solid state lasers, bioimaging, Ge photovoltaic devices (band gap approximately 0.67 eV) and so on.