The work has been carried out by EDS Systems and includes both offshore substations as well as the 160 Siemens 3.6MW turbines.
Speaking about the project, RWE project director Toby Edmonds said: "With all construction activity on the wind farm completed, we're looking forward to progressing towards its ultimate milestone, the final commissioning and operation of the remaining few turbines."
Once complete it will become the world's second biggest offshore project behind the 630MW London Array.
At the end of 2014, RWE announced that physical construction of foundations, turbines, cabling was completed. Since then final cable connection has taken place between turbines and the offshore substation. This week, 10 turbines remain to be commissioned. "This should happen in the next couple of weeks, depending on weather," said a spokesperson for RWE.
Gwynt y Mor started delivering power from the first turbine in August 2013, and by September last year was generating from half of the project.