Abstract: Superconducting nanowires are widely used in quantum computing, superconducting electronics, and low-temperature physics due to their high sensitivity, compact footprint, and low noise. Here, we present a gate-tunable superconducting nanowire thermometer that enables high-precision temperature measurements in the liquid-helium regime by applying a gate voltage. Experimental results demonstrate stable operation in the 2.5-6.2 K range, with a maximum sensitivity of 4.51×10⁵ cps·K⁻¹, indicating the potential for sub-millikelvin resolution. The device further exhibits a minimum noise-equivalent temperature difference (NETD) of 5.5 mK, corresponding to millikelvin-level measurement accuracy. Its on-chip integrability, fast response, and tunable performance make it a promising solution for low-temperature sensing and on-chip thermal monitoring in quantum chips. This work provides an experimental platform and theoretical basis for electric-field-controlled superconducting electronics and highlights the potential of gate-controlled nanowires for integrated cryogenic sensing technologies.