Bitumen extracted from oil sands which is abundant in Canada needs to be partially upgraded to meet pipeline specifications before being sent to downstream refineries. Hydrotreating where expensive hydrogen is involved at high pressure (15-20 MPa) is commonly employed as the technique to satisfy the upgrading requirement. In this study, it is reported that a partially upgraded crude oil can be readily produced from bitumen under a methane environment at mild conditions (400 degrees C and 3 MPa) without H-2 engagement under the facilitation of 1%Ag-5%Mo-10%Ce/ZSM-5 (Si/Al = 23:1). Moreover, methane participation into the upgrading process was evidenced by model compound reactions employing n-butylbenzene as a model compound to typify heavy oil and clearly observed in H-1 and D-2 NMR spectra when CD4 was engaged as the methane source. Through extensive catalyst characterizations using TEM, XRD, and XPS, the excellent catalytic upgrading performance might be closely related to the highly dispersed silver and molybdenum oxide on the zeolite support at reduced oxidation state for better methane activation and partially reduced cerium oxide for coke reduction owing to its high oxygen mobility. The outcomes from this research could not only create an innovative route for more profitable natural gas utilization but also benefit bitumen partial upgrading in a more economical and environmentally friendly way.