We propose a face-sealed encapsulation solution with simple process and low cost. The polyisobutylene encapsulation patch mixed with calcium oxide particles is attached to the surface of the OLEDs that is exposed to the hygroscopic agent in a face-sealing manner. We find that this encapsulation scheme exhibited excellent waterproof performance. The encapsulated OLED has a long shelf lifetime in water under high temperature conditions, which is manifested in a long underwater shelf lifetime of T95 (luminance drops to 95 % of the initial luminance) of over 336 h at 60°C. We believe that this encapsulating technology can be applied to other organic optoelectronic devices, and the face-sealed encapsulating patch is flexible. This strategy can be extended to roll-to-roll processes to expand the application of flexible organic optoelectronic devices underwater.