A waterproof cap for electronic devices includes a cover plate and sealing base located on a surface of the cover plate for sealing a port of a housing of the electronic devices. A first lip and a second lip are located on an outer periphery of the sealing base and are spaced apart from each other. The first lip is located between the cover plate and the second lip. When the sealing base is inserted into the port of the housing of the electronic devices, the first lip is configured to tilt toward the cover plate, and the second lip is configured to tilt away from the cover plate.