The metal-oxide semiconductor-based gas sensor has enthralled many researchers worldwide over past few decades. These sensors offer many advantages such as good selectivity, high sensitivity, and reliable and rapid detection of numerous pollutants. Among the pollutants, CO gas is highly toxic, and CO gas concentration of 9 ppm causes harmful effect on human health; thus, high sensitivity of CO gas detection is extremely significant. Herein, we present the room temperature detection of low concentration CO gas by utilizing cerium oxide microflowers anchored on graphene nanoplatelets (GNPs). The GNPs-CeO2 nanocomposite was synthesized using solvothermal method and followed by structural and morphological characterizations were performed using various analytical techniques. The chemiresistive gas sensor was fabricated with a nanocomposite solution drop-casted on cellulose paper as a substrate and silver paste as an electrode. The as-fabricated gas sensor explored for its applicability on CO gas detection with various concentrations and displayed good selectivity over NO2, SO2, NH3, and CO2. The gas sensing response of the device is due to large number of oxygen vacancies in the nanocomposite and the heterojunction between CeO2 and GNPs. The sensor offers a potential platform for metal oxide-based gas sensors operated at room-temperature and displayed good repeatability and stability. © 2021