This paper presents the full-custom design of a 45 nm microprocessor using the electronic design automation (EDA) software, Microwind. The design consists of fundamental modules: The arithmetic logic unit (ALU), memory, counter and an integrated Bluetooth (BT) port working at the 2.4 GHz. This design is validated by simulation under a process, voltage, and temperature (PVT) testing. The microprocessor can handle up to 4 bit since its purpose is focused on specific applications such as the internet of things (IoT). In order to communicate to the external world and with other devices, a strong input/output data interface and radio frequency (RF) transmission modules are implemented. Moreover, the RF module also contains a Bluetooth communication, which allows the wireless data transmission from/to the microprocessor.