Co vacancy (VCo) induced robust room temperature ferromagnetism (Ms∼ 60 emu/cm3 and coercivity∼ 603 Oe) is experimentally realized in rock-salt CoO epitaxial thin film (∼ 110 nm) grown by pulsed laser deposition. Co charge state is found to be higher∼+ 3.2 (from Co L3/L2 white line ratio) and this is due to the VCo induced charge transfer from the neighboring Co-3d to O-2p states in order to compensate for the hole formation. OK and cathodoluminescence spectra corroborate the existence of VCo and higher charge state. Temperature dependent magnetization and exchange bias experiments confirm the coexistence of ferromagnetic and antiferromagnetic phase