The world’s oceans hold enormous energy resources but are vastly left unutilised due to underdeveloped technology. Ocean wave energy exploration is steadily rising with Oscillating Water Column (OWC) Wave Energy Converter (WEC) device taking the lead all around the world. Offshore devices are being preferred and researched upon recently as the energy of the waves is diminished by the time they reach the shore. Moreover, to mitigate the cost of construction through cost-sharing methods, these WECs are being integrated into other marine structures such as ports, groynes, and breakwaters. In the current study, a freely floating offshore U-shaped OWC device integrated with a Π-shaped breakwater under the action of regular as well as irregular waves is analysed. The performance of the integrated device is assessed based on the added mass and radiation damping coefficients in sway, heave, and roll modes of motion as well as the maximum theoretical efficiency, radiation susceptance, and radiation conductance coefficients. The influence of geometric variations such as width of the U-OWC chamber on the hydrodynamic performance is analysed. Boundary Element Method (BEM) is used to evaluate the unknown potentials and subsequently calculate the required coefficients. Similar to the case of conventional OWC devices, the peak efficiency of the integrated U-OWC with breakwater is observed whenever resonance occurred. The study found that increasing internal chamber width of the U-OWC improves the energy conversion efficiency. The sway, heave, and roll mode added mass and damping coefficients increase with increase in chamber width. An overall wider structure leads to larger volume, and mass which leads to greater motions. The study will be helpful to scientists and engineers for the design and analysis of an effective floating integrated WEC-breakwater system.