Currently, there is growing interest in non-antibiotic treatments due to the emergence of multidrug-resistant bacteria. Moreover, photodynamic therapy is advantageous as it is non-invasive and does not lead to resistance development. Unlike traditional light therapy platforms, such as light amplification by stimulated emission of radiations (LASERs) and light-emitting diodes (LEDs), organic LEDs (OLEDs) are lightweight, flexible, and compact, enabling real-time treatment in everyday life. Additionally, as a surface-emitting light source, OLEDs deliver a uniform treatment effect over a large area. In this study, we explored the synergistic effect on Staphylococcus aureus (S. aureus) using a natural non-antibiotic material, Sanguisorba officinalis L. extract solution (SO. L.), and 465 nm peak patchable OLEDs depending on both irradiation time and light source area at an intensity of 17 mW/cm². The results confirmed that antibacterial activity increased with light exposure to SO. L., and further increased as the area of the surface light source expanded. Moreover, the effect was noted with another natural non-antibiotic material. This study validated the non-antibiotic treatment using antibacterial synergistic activity between natural antibacterial phytochemicals and OLEDs and its free-standing antibacterial activity against antibiotic resistance in S. aureus.