Grid-connected inverters are conventionally controlled in synchronously rotating frame of reference with the controllers being designed for steady state operation via small signal modeling neglecting higher order and coupling terms. However, for an inverter connected to the grid via RL filter, cross coupling terms are present due to transformation to synchronously rotating dq reference frame, thereby affecting the dynamic performance. In this paper adaptive estimation based feedback linearization control is proposed for online parameter update to exactly cancel the non-linearity and higher order terms which reduces the system into bunch of pure integrators. The details of adaptive parameter estimation and the feedback linearization have been presented in this paper. Overall control architecture proposed in this paper is been verified via simulation studies based on MATLAB/Simulink and Plecs domain. A reduced scale laboratory prototype has been utilized to implement the proposed control architecture and verify its efficacy.