To meet the requirements of wide-temperature reliability and fast transient response in power management ICs for automotive, aerospace, and industrial applications, this paper presents a fast-response low-dropout regulator (LDO) based on a 0.18 μm high-temperature SOI process. Benefiting from the buried oxide isolation structure of the SOI technology, leakage current and parasitic effects under high-temperature conditions are effectively suppressed. The proposed LDO employs an NMOS power transistor, with an on-chip charge pump used to enhance the gate driving capability. In addition, a triple-loop regulation scheme consisting of a main negative feedback loop, an auxiliary positive feedback loop, and a current-mode feedback loop is adopted to improve transient performance and enhance loop stability. The fabricated chip occupies an area of 2840 μm × 1490 μm and supports an input voltage range of 3–5.5 V and an output voltage range of 1.2–3.3 V. Over a temperature range of −55 °C to 175 °C, the LDO can deliver a maximum load current of 400 mA. At 175 °C, the measured overshoot and undershoot voltages are 64 mV and 94 mV, respectively, with a maximum recovery time of 336 μs. Moreover, the power supply rejection ratio (PSRR) reaches 56.8 dB at 100 Hz. Experimental results demonstrate that the proposed LDO exhibits excellent high-temperature adaptability, strong load-driving capability, and superior transient response performance.