A RFID-to-Bluetooth selective adapter which includes a customized RFID transponder with an on/off switch, a RFID sensor coil, and a Bluetooth module with an EEPROM memory is disclosed. The RFID-to-Bluetooth selective adapter can be attached to a RFID doorlock to operate in both RFID mode and Bluetooth modes without interference therebetween, so as to use by RFID tags or smartphones, respectively. The RFID reader equipped device can be a RFID smart doorlock; a door is configured with the RFID smart doorlock and the RFID-to-Bluetooth selective adapter is mounted thereon, and the door can be opened and closed using the APP by the authorized user in real-time with or without internet connection. The RFID-to-Bluetooth selective adapter functions as a bridge between the RFID reader equipped device and smartphone operating under Bluetooth smart. In addition, the RFID-to-Bluetooth selective adapter possesses several security upgrade options.