Airflow rate has a significant impact on the performance of oscillating water column (OWC) wave energy converters (WEC). A novel method is proposed in this work that improves airflow rate and output power by integrating a mechanical component referred to as a windcatcher with a conventional OWC or known as a hybrid OWC. A non-linear two-dimensional computational fluid dynamics (CFD) approach is used, together with the Reynolds Averaged Navier-Stokes (RANS) technique, to explore the hydrodynamic performance of the proposed system. Simulation studies are conducted and the results of the proposed hybrid OWC are superior in terms of airflow rate and output power compared to a conventional design. Furthermore, as the amplitude of the oscillatory element of the turbine airflow rate is reduced, the results reveal a consistency in generating power in the proposed hybrid OWC system. As a result, the proposed hybrid OWC converter produces much more power than a conventional model. There are two parts to this study. The results of the first part of the study reveal that the geometry of the proposed system is not perfect, and there is a discrepancy between the simulation result and the maximum turbine airflow rate, which is the sum of wind and wave airflow rate. As a result, the geometry should be modified to achieve optimum turbine airflow rate. Therefore, the effect of changing key geometric variables such as turbine height, orifice width, and orifice output angle on the performance of the proposed hybrid system is analyzed in the second part of this study. The turbine flow rate, chamber pressure, orifice flow rate, and turbine power output are selected to monitor the performance of the proposed system under different geometrical situations. Eventually, the values of the chosen geometrical parameters at which the proposed system achieves the best performance indicators are determined.