Low-frequency inter-area oscillation is a critical concern in the inter-linked power system. Numerous investi-gations are being carried out in order to damp these inter-area oscillations. High-voltage direct current (HVDC) links are now available to adequately mitigate these oscillations, while strengthening system stability. Hence, in this work, a robust wide area damping controller (WADC) is designed to modulate the power flow through HVDC tie-line for damping inter-area oscillation in power system. First step involves the determination of crucial inter-area modes by using modal analysis approach. Next, geometric technique is used to choose an appropriate wide-area feedback signal. Then, based on above information a robust $H_{\infty}$ controller is designed in order to effectively damp out inter-area oscillation. Finally, the proposed WADC is validated on HVDC integrated 4-machine 11-bus system to ensure its efficacy.