In this paper, a multi-port hybrid nine-arm modular multilevel converter is proposed for integration of an offshore wind farm into the HVDC subsea power transmission system feeding an offshore subsea oil and gas processing load. A detailed analysis of circulating current of the proposed converter is performed and accordingly, a control architecture based on a synchronous rotating reference frame is developed. The proposed control architecture regulates the circulating current at an optimal value in order to achieve a stable and efficient operation of the multi-port hybrid nine-arm modular multilevel converter. The proposed architecture incorporates control of phase angle difference between the source port and load port voltages, which is the key to regulate the circulating current magnitude. A system level simulation model has been developed on PLECS simulation software to demonstrate the performance of the proposed control architecture. © 2020 IEEE.