<p>To capture energy from waves, an oscillating buoy (OB) is one of the well-established wave energy converters due to its simple construction and ability to extract energy efficiently. Further, with optimal wave focusing by a parabolic wall, the wave energy devices can extract significantly more energy compared to the standalone condition. Considering these advantages, this study presents a comprehensive investigation into the heave response characteristics and energy capture performance of a cylindrical OB integrated with a parabolic wall. A series of experimental and numerical analyses has been conducted under regular and random wave conditions to evaluate the influence of wall geometry, Power Takeoff (PTO) damping, and the diameter of the buoy. Among the configurations tested, the OB integrated with a parabolic wall demonstrated the highest Heave Response Amplitude Operator (HRAO) and capture width ratio (CWR), benefiting from the wave-focusing effect of the structure. It achieved a maximum of 2.7 times higher HRAO and 10 times higher CWR compared to the standalone OB under regular waves. The heave response and energy absorption were optimum when the OB diameter was approximately half the focal length of the parabolic wall. The CWR is observed to be maximum when the PTO damping matched with the hydrodynamic damping of the buoy for all the configurations at resonance condition. To enable sustained energy harvesting, it is recommended to design the OB such that its natural frequency aligns with the wave frequency corresponding to maximum amplification induced by the parabolic wall, ensuring optimal energy conversion.</p>