A shell assembly, and an electronic device and a mobile phone having the same are provided. The shell assembly includes a shell and at least one reinforcing pillar. The shell includes a plate and a side plate extending from the plate. The plate and the side plate cooperatively defines a receiving cavity at least configured for receiving a battery. The at least one reinforcing pillar is received in the receiving cavity. When the battery is received in the receiving cavity, the at least one reinforcing pillar is positioned between the battery and the side plate.