The consequences of carbon nano materials incorporation for gas sensing applications received noteworthy consideration in the recent preceding years. Owing to their desirable physical and chemical specification, the carbon nanomaterials and combinations with other materials are well suited for the gas sensing applications as it satisfies the condition of elevated surface area and reduced bandgap. Herein, we start this review by reviewing the importance and preparation methods of carbon nanomaterials. Varied carbon based nanomaterials as carbon nanoonions, carbon nanohorns, nanodiamonds and carbon quantum dots are explored. Graphene and its derivatives are normally combined with CNTs, thus. We introduce after that the graphene synthesis, specifications, and graphene/metal oxides, noble metals, and polymers nanocomposites for gas sensing. This review summarized the keypoints for the gas sensing area that relied on carbon nanomaterials. Furthermore different types of sensors toward different gas species have been reported and discussed.