In this study, a series of humidity sensors based on graphene/SnO2 (Gr/SnO₂) nanocomposites with different proportions of the sensing material (10, 20, 30, 40, 50, and wt%) have been successfully fabricated by a simple method. The surface design, chemical structural information, and elemental variation of the prepared humidity sensors were investigated using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDXS) and transmission electron microscopy (TEM). By measuring the sensitivity, hysteresis, response characteristics of the humidity sensors, it was proved that the obtained 30 wt% Gr/SnO₂-based humidity sensor exhibited outstanding fast response/recovery speeds (28/140 s), small hysteresis (~5% RH), and high humidity sensitivity (S＝80770) in the 12–90% RH range. Therefore, Gr/SnO₂ can be used as a potential material for real-time humidity-sensing applications.