Reduced graphene oxide (rGO) gas sensors functionalized with platinum (Pt) nanoparticles were fabricated. An alternating current dielectrophoresis technique was used for the precise alignment of the Pt-GO nanohybrid between microgap electrodes, proceeded by the mid-temperature thermal annealing. The gas sensing response was determined for the assembled rGO nanostructure-based devices with and without Pt decoration at various ambient temperature and gas concentrations. The tested device exhibited sensitivities of 14% (7%), 8% (5%), and 10% (8%), for 1000 ppm hydrogen, ammonia, and nitric oxide gases, respectively with (without) Pt nanoparticles, at room temperature. The Pt-decorated samples show an improvement of 100%, 60% and 25% to hydrogen, ammonia, and nitric oxide gases, respectively, over without Pt decorated sensors. Besides, improving the sensitivity, the dielectrophoresis assembled rGO-Pt nanohybrid sensors have been demonstrated as a viable material for multiple gas sensors.