This paper suggests a novel non-linear synergetic control for a unified power flow controller (UPFC). UPFC is a member of flexible AC transmission system devices, that controls power flow and regulates the voltage by enhancing the transient stability of the power system. UPFC comprises of two voltage source converters (VSCs). Equations of VSC are inherently non-linear. In this paper, we propose a non-linear approach to control the UPFC based on the synergetic control technique. It is simple to implement and valid for a variety of operations. It is also effective in suppressing inter-area oscillations. To verify the effectiveness of the proposed controller, various case studies are simulated and the results are compared with the traditional linear and non-linear controllers.