Transparent conductive and flexible Mg and Ga co-doped ZnO (MGZO) thin films were prepared on poly-ethylene terephthalate (PET) by RF magnetron sputtering technique at room temperature. The effects of different working pressures on the structural, chemical, morphological, optical and electrical properties of MGZO thin films were investigated. X-ray diffraction results indicate that all the MGZO thin films were grown as polycrystalline wurtzite structures without secondary phases such as MgO, Ga2O3, MgGa2O4, or ZnGa2O4. The MGZO thin film prepared at 6 mTorr has the lowest value of full width at half maximum. A typical survey spectrum of all the MGZO thin films confirmed the presence of Mg, Ga, Zn and O. The MGZO thin film prepared at 6 mTorr showed the widest optical band gap energy of 3.91 eV and lowest electrical resistivity of 5.3 × 10−3 Ω cm.