Abstract: Offshore wind energy has experienced rapid development because of its abundant wind resources and high energy potential. Previous studies have demonstrated that wave effects on airflow can substantially influence wake recovery and power production in offshore wind farms by modifying the air–sea momentum exchange. In this study, we aim to investigate how wave age and propagation direction modulate the power performance and energy transport characteristics of offshore wind farms. We use a Large-Eddy Simulation (LES) method coupled with a Mean Kinetic Energy (MKE) budget analysis framework. Results show that the overall power output consistently increases with wave age. When the wind–wave system is obliquely to the wind turbine array, it yields higher power output than aligned inflow. However, this advantage decreases as wave age increases. The MKE budget agrees with the power variations, identifying turbulent transport as the dominant energy supply to the turbine layer. Control-volume flux diagnostics further reveal that the turbine layer is primarily replenished through downward turbulent transport from the upper boundary layer, while the underneath wave forcing enhances the net vertical energy input. Compared with aligned inflow, oblique inflow redistributes energy transport pathways by strengthening net lateral energy transport contribution. This, thereby, increases the mean kinetic energy supplied to the turbine layer and consequently improves wind-farm power production. These findings suggest that wave effects modulate energy-replenishment pathways within the marine wind turbine array boundary layer, providing new physical insights into the coupled wave–wind–farm interaction under complex sea states.