Convective heat transfer can be enhanced by changing flow geometry and/or by enhancing thermal conductivity of the fluid. In this work, CFD modelling of horizontal straight and curved channel with square cross section were presented to investigate the effect of hybrid nanofluids on turbulent forced convective heat transfer. This study proposes simultaneous passive heat transfer enhancement by combining the geometry effect using 0.1% graphene nanoplatelets-silver hybrid nanofluids (GNP–Ag) inflow in straight and curved channel. The results showed that the average Nusselt number is generally higher for curved channel with hybrid nanofluid when compared with straight square channel. Moreover, for 0.1% of GNP–Ag hybrid nanofluid improvement is 22.61% and 34.78% for straight channel and 27.43% and 39.52 for curved channel at the Reynolds number of 5,000 and 17,500, respectively.