[en] Highlights: • The Ca₂LaSbO₆:Eu³⁺ red phosphor with double perovskite structure has been synthesized. • The phosphor exhibit high quantum efficiency and excellent thermal stability. • The PiG composite is obtained by introducing the YAG:Ce³⁺ and Ca₂LaSbO₆:Eu³⁺ into TeO₂-based glass. • The constructed w-LEDs exhibit superior optical performance and tuned chromaticity. • The PiG-based warm w-LED yields an admirable CCT of 3993 K and CRI of 86.7. Phosphors-in-glass (PiG), which serves as a potential bi-replacement of both phosphors and organic encapsulants in high-power white light-emitting diodes (w-LEDs), has captured much attention due to its high thermal conductivity and excellent thermal stability. Aiming to tune the correlated color temperature and color rendering index of YAG:Ce³⁺ PiG-based LED device, an efficient phosphor play an important function as red components are in demand to incorporate into the PiG composite. In this study, the Ca₂LaSbO₆:Eu³⁺ red phosphor with double perovskite structure has been synthesized through a high-temperature solid-state reaction. The quantum efficiency of the as-obtained phosphor reaches as high as 81%, and its luminescence intensity can remain above 80% at the temperature below of 423 K. Subsequently, the high-efficiency Ca₂LaSbO₆:Eu³⁺ and commercial YAG:Ce³⁺ phosphors are incorporated into the TeO₂-based glass to form the PiG composite. Impressively, the original emissive properties of the embedded phosphor particles are retained. Finally, the PiG encapsulated high-power w-LEDs are fabricated, exhibiting improved chromaticity feature and superior optical performance. By adjusting the mass ratio of Ca₂LaSbO₆:Eu³⁺ red phosphor to YAG:Ce³⁺ yellow one in the PiG composite, a tunable correlated color temperature ranging from cool white (6665 K) to warm one (3993 K) and the color rendering index increasing from 70.6 to 86.7 are achieved. Especially, the structured warm w-LEDs exhibits good color stability under different drive currents.