The objective of this paper is to numerically study the heat transfer and hydrodynamic performance of a graphene-based hybrid nanofluid flowing through a microchannel for electronics cooling applications. Different concentrations of Graphene-Platinum/water hybrid nanofluid were employed as coolants. The thermophysical properties used in this study were considered to be temperature-dependent. The microchannel was modeled as a porous media. The effect of nanoparticle volume concentration on thermal resistance, pressure drop, friction factor and ratio of heat transfer coefficient to pressure drop (Figure of merit) was analyzed and the plots were generated for different Reynolds numbers of the working fluid. The results pointed out that introduction of nanoparticles resulted in the lowering of thermal resistance. However, the pressure drop and friction factor increased. Figure of merit is found to be higher for higher concentrations of hybrid nanofluids compared to base fluid water. On analyzing the results, it was understood that the utilization of Graphene-Platinum/water hybrid nanofluid through microchannels can be highly effective in the laminar region. It also suggests that this graphene based nanofluid has excellent potential as a coolant to remove excess heat from miniature electronic devices.