The infinite potential of lanthanide in optoelectronic research has triggered the search for ideal host materials. Herein, based on the excellent lanthanide compatibility of double perovskite La₂MgTiO₆, light-responsive multifunctional phosphors with four modes were successfully constructed (Modes I–IV: Tm–Yb; Er–Yb; Ho–Yb; Er/Tm–Yb). After systematically exploring the internal mechanism of high-purity and brightness upconversion (UC) photoluminescence behind the four modes, intense green, blue and near-white lighting-emitting diodes (LEDs) were fabricated. Besides, aiming at the different emission energy levels of the monitored bands, the temperature-sensing performance of Modes I–IV was strictly evaluated utilizing thermally coupled or non-thermally-coupled luminescence intensity ratio (LIR) techniques. All the modes demonstrate excellent temperature measurement potential, stability and repeatability. Especially in Mode IV, a novel self-calibrating partition thermometer with dual-emitting centers originating from Er/Tm was designed successfully, which can provide specific LIR for three regions of low temperature, medium temperature and high temperature, and finally achieve high relative sensitivity over an ultra-wide temperature range. The results testify that the as-synthesized multifunctional phosphors break through the limitation of lanthanide doping types in a single material, which can realize the diversification of application functions and launch a new chapter for the design of advanced multifunctional materials.