In this present work, we synthesized reduced graphene oxide/Tungsten trioxide (rGO/WO3) nanocomposites through hydrothermal method. We discussed the implication of charge transfer between Tungsten trioxide (WO3) and reduced graphene oxide (rGO) through steady-state fluorescence quenching with fitting. In addition, we report nonlinear optical (NLO) properties of GO, WO3 and rGO/WO3 at 532 nm employing the open aperture Z Scan technique. UV spectroscopy reveals the bandgap variation due to rGO addition. The rGO/WO3 nanohybrids shows the low saturation intensity Is and 0.5 × 1011 W/m2 compared to the WO3 saturation intensity Is ~ 1 × 1013 W/m2. The results displays that the effective charge transfer between WO3 and rGO leads to the band-gap variation and enhances the SA performance of the nanohybrids. Results shows that these nanohybrids are potentially useful for mode locking, optical switching and as a saturable absorber. Moreover, the structural property was confirmed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) images supports the nanohybrids as nanorods and vibrational properties were analyzed by Fourier transformed Infrared Spectroscopy (FTIR) technique.