The　dedicated　control　of　lanthanide-mediated　energy　migration　within　a　nanostructure　can　help　realize　plenty　of　intriguing　luminescence　behaviors.　In　this　work,　an　Er3+-sensitized　upconversion　emission　of　Tm3+　by　means　of　Yb3+-mediated　energy　migration　has　been　firstly　realized　with　a　core/shell　nanostructure.　The　analysis　of　the　luminescence　thermal　behavior　of　the　nanostructure　indicates　that　the　heating-induced　alleviation　of　energy　migration-mediated　surface　quenching　leads　to　the　thermal　enhancement　of　Tm3+　emission,　while　the　green　emissions　of　Er3+　exhibit　thermal　quenching.　By　leveraging　the　thermal　quenching,　heating-induced　alleviation　of　surface　quenching　and　the　characteristic　of　thermally　coupled　levels,　specifically,　a　ratiometric　luminescent　nanothermometer　has　been　developed　via　the　combination　of　emissions　from　both　Tm3+　and　Er3+,　which　exhibits　a　high　relative　sensitivity　up　to　3.46%　K−1.　This　work　may　offer　a　promising　design　route　toward　luminescent　nanothermometers.　©　2025　The　Royal　Society　of　Chemistry.