Abstract: Rare-earth nickelates (RENiO₃) show widely tunable metal-to-insulator transition (MIT) properties with ignorable variations in lattice constants and small latent heat across the critical temperature (T_MIT). Particularly, it is worth noting that compared with the more commonly investigated vanadium oxides, the MIT of RENiO₃ is less abrupt but usually across a wider range of temperatures. This sheds light on their alternative applications as negative temperature coefficient resistance (NTCR) thermistors with high sensitivity compared with the current NTCR thermistors, other than their expected use as critical temperature resistance thermistors. In this work, we demonstrate the NTCR thermistor functionality for using the adjustable MIT of Nd_xSm_1−xNiO₃ within 200–400 K, which displays larger magnitudes of NTCR (e.g., more than 7%/K) that is unattainable in traditional NTCR thermistor materials. The temperature dependence of resistance (R–T) shows sharp variation during the MIT of Nd_xSm_1−xNiO₃ with no hysteresis via decreasing the Nd content (e.g., x ≤ 0.8), and such a R–T tendency can be linearized by introducing an optimum parallel resistor. The sensitive range of temperature can be further extended to 210–360 K by combining a series of Nd_xSm_1−xNiO₃ with eight rare-earth co-occupation ratios as an array, with a high magnitude of NTCR (e.g., 7%–14%/K) covering the entire range of temperatures.