At present, with the increasing application needs of phosphor-converted white light-emitting diode (w-LED), the synthetic efficiency and thermal stability of phosphor become urgent problems. Herein, this research reports a microwave-assisted fast synthesis approach to obtain a Sm3+-activated borotellurate Na2Y2TeO4(BO3)2 (NYTB) red phosphor with high crystallinity, excellent thermostability, and low chromaticity shift. For the NYTB-based phosphor, in contrast to the conventional solid-state synthesis, the microwave-assisted synthesis method involves lower synthesis temperature and shorter processing time. Additionally, the concentration quenching mechanism was determined. The w-LED device packaged with the studied phosphor exhibits a near-standard white light with proper CCT and high Ra parameters.