The development of nonlinear optical materials with strong multiphoton absorption (MPA) is crucial for the design of ultrafast nonlinear optical devices, such as optical limiters and all-optical switchers. In this study, we present the wavelength-dependent coefficients of two-photon absorption (2PA) and three-photon absorption (3PA) in a GaS film across a broad range of wavelengths from 540 to 1600 nm. The observed dispersions in the 2PA and 3PA coefficients align well with the widely used two-band approximation model applied to direct bandgap semiconductors. Notably, the GaS film exhibits exceptional MPA properties with a maximum 2PA coefficient of 19.89 cm/GW at 620 nm and a maximum 3PA coefficient of 4.88 cm³/GW² at 1500 nm. The GaS film surpasses those found in traditional wide-bandgap semiconductors like β-Ga₂O₃, GaN, ZnO, and ZnS while remaining comparable to monolayer MoS₂, CsPbBr₃, and (C₄H₉NH₃)₂PbBr₄ perovskites. By employing a simplified two-energy-level model analysis, our results indicate that these large MPA coefficients are primarily determined by the remarkable absorption cross sections, which are approximately 4.82 × 10^-52·cm⁴·s·photon^-1 at 620 nm for 2PA and 8.17 × 10^-80·cm⁶·s²·photon^-2 at 1500 nm for 3PA. Our findings demonstrate significant potential for utilizing GaS films in nonlinear optical applications.