An electronic device with a projection functionality includes: a universal serial bus (USB) port, a processing circuit, a storage, a storage controller and a display circuit. The USB port receives USB packets carrying a first pixel data. The processing circuit is coupled to the USB port, and converts the received USB packets into the first pixel data. The storage controller is coupled between the processing circuit and the storage, and stores the first pixel data into the storage. The display circuit is coupled to the storage controller, and generates a display driving signal according to the first pixel data stored in the storage.