Using full-potential linearized augmented plane wave (FLAPW) method, we investigated the effects of intrinsic vacancies on electronic and magnetic properties in graphene-like ZnO nanosheets. The results show that the oxygen vacancy (V-O) has no influence on magnetism in ZnO nanosheet, whereas the Zn vacancy (V-Zn) lead to spin polarization of the nanostructures with a total magnetic moment of 2.0 mu(B) due to O-2p and Zn-3d hybridization. When the distance of two V-Zn defects increases to 6.499 angstrom, the system shows an intriguing half-metallic character with 100% spin-polarized carriers due to O(2p)-Zn(3d) -O(2p) coupling chain between two V-Zn defects. (C) 2012 Elsevier B. V. All rights reserved.