Power systems continuously subjected to various types of disturbances, which cause a lot of power system instability which lowers its efficiency. Power loss is the major one which decreases the efficiency of electrical machine, disturb the quality and stability of the system, decrease the revenue of the government, and affect customer satisfaction. Minimization this loss is very important to increase distribution and transmission power flow. Power loss reduction have been focused in this research to solve the challenges happens in transmission systems. The contribution of this work presents loss minimization of the Bahir Dar to Debremarkose power transmission using a unified power flow controller (UPFC) applied in North West Region of Ethiopian power system network. This method is selected for loss minimization due to its versatility or its ability to control all power system parameters like active power, reactive power, bus voltage, line impedance and load angle. The research is properly modeled and conducted using MATLAB/SIMULINK software. The SIMULINK model contains both North West Region power system network and the UPFC. Power loss measurement of the transmission line has been conducted in different scenarios. The power loss measurement of the transmission line under steady state condition is 2.048MW. However, when UPFC is connected to the power system network of the North West Region, the loss of the transmission line is reduced to 85.12kW and hence 1.69MW power is saved from the transmission line by using UPFC. When the power system network is exposed to three phase fault at 230kV distribution network and the fault sustained from 0.1-0.5seconds, the loss becomes 2.0482MW. However, when UPFC is used, the power loss becomes 82.21kW. Hence, at least 1.963MW power is saved from loss wasted by the transmission line using UPFC.