The present paper investigates a hybrid breakwater-oscillating water column (OWC) system by integrating a heaving floater wave energy converter (WEC). Both the water oscillating of the OWC and the wave-induced relative motion of the floater hinged in front of the OWC device are employed to extract wave energy. A three-dimensional wave tank is numerically modelled by Star-CCM + Computational Fluid Dynamics (CFD) software to investigate the hydrodynamic performance of the hybrid system. The hydrodynamic characteristics of symmetric and asymmetric floaters in terms of wave attenuation and energy extraction performance are examined. Four floaters with different bottom shapes are considered. The results indicate that the asymmetric floaters lead to a higher capture width ratio (CWR) and better wave attenuation performance, such that CWR of the hybrid system integrated with the Berkley Wedge bottom shape can reach up to 81.2%. The effects of the radius ratio, the submerged opening height, and the distance between the oscillating buoy (OB) and OWC device are further analyzed. The findings of this paper reveal that the geometrical parameters of the hybrid system have significant effects on wave energy absorption efficiency and hydrodynamic performance. The results provide advice on the design of wave energy devices.