A current source converter (CSC) based static synchronous compensator (STATCOM) is a shunt flexible AC transmission system (FACTS) device, which has a vital role as a stability support for small and large transient instability in an interconnected power network. A robust linear quadratic regulator (LQR) based controller for CSC-STATCOM is proposed. In this paper, LQR based CSC-STATCOM is designed to enhance the transient stability of two-area two-machine power system. First of all, modeling & LQR based controller design for CSC-STATCOM are described. After that, the impact of the proposed scheme on the test system with different disturbances is demonstrated. The feasibility of the proposed scheme is demonstrated through simulation in MATLAB and the simulation results show an improvement in the transient stability of power system with CSC-STATCOM. Also, the robustness and effectiveness of CSC-STATCOM are better rather than other shunt FACTS devices (SVC & VSC-STATCOM) in this paper.