We report that non-contact self-referencing temperature sensors can be realized with the use of core–shell nanostructures. These lanthanide-based nanothermometers (NaGdF₄:Yb³⁺/Tm³⁺@Tb³⁺/Eu³⁺) exhibit higher sensitivity in a wide range from 125 to 300 K based on two emissions of Tb³⁺ at 545 nm and Eu³⁺ at 615 nm under near-infrared laser excitation.