Amorphous Zn–In–Sn–O (ZITO) films are grown by an rf magnetron cosputtering system from ceramic oxide targets of ZnO and ITO onto a flexible polyether sulfone (PES) substrate. The films exhibit resistivity as low as 1.22 × 1 0 − 3 Ω cm and optical transparency comparable to greater than that of Sn-doped indium oxide (ITO) films. The amorphous ZITO films have good mechanical durability compared to ITO films against the external dynamic stress measured by the bending tester. The deposited ZITO film has been used as a transparent anode in fabrication of the flexible organic light-emitting diode (OLED) by the cluster organic evaporator system. The amorphous ZITO anode-based flexible OLED shows comparable or superior current density and luminance characteristics compared to that of the amorphous ITO-based OLED.