A metallic housing for an electronic device, the metallic housing includes a main body defining a receiving chamber for receiving electronic components and an opening communicating with the receiving chamber, and a covering plate positioned on the main body adjacent to a side of the main body. The covering plate is welded to the main body by friction stir welding and a welded region is formed on a side surface of the metallic housing such that the welded region is smooth with the main body and the covering plate. A method for making the metallic housing and an electronic device using the metallic housing is also disclosed.