A novel nonenzymatic sensor based on cobalt (II) oxide (CoO)-decorated reduced graphene oxide (rGO) was developed for the detection of carbofuran (CBF) and carbaryl (CBR). Two well-defined and separate differential pulse voltammetric peaks for CBF and CBR were obtained with the CoO/rGO sensor in a mixed solution, making the simultaneous detection of both carbamate pesticides possible. The nonenzymatic sensor demonstrated a linear relationship over a wide concentration range of 0.2–70 μM (R = 0.9996) for CBF and 0.5–200 μM (R = 0.9995) for CBR. The lower detection limit of the sensor was 4.2 μg/L for CBF and 7.5 μg/L for CBR (S/N = 3). The developed sensor was used to detect CBF and CBR in fruit and vegetable samples and yielded satisfactory results.