Inverted organic solar cells (OSCs) with high efficiency and flexibility have been demonstrated. A thick Ag film with ultrasmooth morphology fabricated on a photopolymer substrate by template-stripping process and a semitransparent Ag film has been employed as cathode and anode of the top-illuminated OSCs, respectively. An improved performance has been obtained compared with that of the OSCs deposited on Si substrate due to the enhanced charge extraction and reduced charge loss resulted from the employment of the ultrasmooth cathode. Moreover, the flexible OSCs obtained by this method keep good performance under a small bending radius and after repeated bending.