The system called Smart Door Locking System using Bluetooth-based Android smartphone. This system presents the design and implementation of a low cost but yet flexible and secure mobile phone based door lock system. The design is based on a standalone Arduino board and the door lock appliances are connected to the input/ output ports of this board. The communication between the cell phone and the Arduino board is wireless. This system is designed to be low cost and scalable allowing variety of devices to be controlled with minimum changes to its core. Password protection is being used to only allow authorized users from accessing the required appliances.