Wave energy is a significant source of renewable energy which is harnessed by wave energy converters (WECs). However, the high levelised cost of energy (LCoE) associated with wave energy projects hinders the commercial development of WECs. To minimise the LCoE, comprehensive control strategies, to maximise electric energy production, are essential. The oscillating water column (OWC) is one of the most promising WECs for harnessing wave power, especially due to its relative simplicity of operation. Due to the overbearing issue of turbine efficiency, the vast majority of OWC control strategies focus on a simplified control objective, namely turbine efficiency maximisation. However, it is important to note that rotational speed control impacts generator performance. Additionally, for Wells turbines, rotational speed control also affects the hydrodynamic performance, specifically the wave-to-pneumatic energy conversion process. Therefore, Wells turbine rotational speed should be ideally modulated to improve the overall wave-to-wire (W2W) efficiency of the OWC system, rather than just turbine efficiency. In this paper, a control strategy for maximising W2W efficiency of a fixed OWC WEC, equipped with a Wells turbine, is designed. The proposed control strategy comprises two parts: Firstly, a ‘global’ setpoint, which considers the entire OWC W2W model, is derived. Secondly, a Lyapunov-based nonlinear controller is designed to track the aforementioned setpoint. Results from numerical simulation show that, in comparison to the somewhat traditional turbine efficiency maximising control approach, the proposed W2W control strategy significantly improves W2W efficiency for the considered sea states.