This paper presents an innovative method of high temperature sustainable chirped fiber Bragg grating (FBG) fabrication from the uniform regenerated FBG or their combination written by a single uniform phase mask. A thermal stretching technique is employed that modifies the grating structure of uniform FBGs, resulting in chirped FBGs capable of withstanding high temperatures without compromising their sensing capabilities. Thermal regeneration of uniform FBG was carried out at 850 °C by applying step annealing schedule. Thermal stretching of single regenerated FBG and dual regenerated FBG was carried out for the fabrication of high temperature chirped FBG. For both approaches, the FBG was stretched by applying strain ∼1200 µε along the length of the grating. In the single FBG approach, the chirped grating with reflection intensity 4500 (A.U.) and bandwidth ∼ 7.1 nm was fabricated by applying thermal gradient from 860 °C to 900 °C across the length of strained thermally regenerated FBG. In double grating approach, the chirped FBG with reflection intensity 6000 (A.U.) and bandwidth 12.7 nm was fabricated. The fabricated chirped FBG can sustain temperature upto 900 °C. This innovative method not only extends the operating range of chirped FBGs to high temperatures but also opens up new possibilities for fabricating chirped FBGs of longer length and bandwidth using low-cost uniform FBGs.