•Graphene (GR)-based electrochemical sensors and biosensors are reviewed in detail.•We describe the advantages and disadvantages of GR- based sensing technologies.•We compared all the sensing systems in terms of their precision, reproducibilities, regeneration capacity, stabilities, and specificities.•More than 150 studies that have used GR are discussed. Graphene (GR), the thinnest and the lightest sp2 carbon nanomaterial, has exhibited extraordinary properties in terms of fast electron mobility, high current density, high mechanical strength, excellent thermal conductivity, and ultra-larger surface area. These characteristics make GR an ideal nanomaterial for nanoelectronics, nanodevices, and nanocomposites. GR-based biosensors, thus, have attracted great attention toward providing a novel sensor platform for analyzing the target biomolecules with high sensitivity and selectivity. Moreover, GR has been used in chemical sensors because of its excellent electrochemical properties. Using GR and GR derivative-modified electrodes, enzyme and DNA biosensors, immunosensors, and chemical sensors have been developed. In this review, the methods of immobilization involved in developing biosensors and chemical sensors have been summarized in Tables. Moreover, the linear ranges, limits of detection (LODs), reproducibilities, and reusabilities of these reported biosensors and chemical sensors are compared in detail. Future prospects in this rapidly developing field are also discussed.