The 161st and final inter-array cable was installed by Reef Subsea's Polar Prince and Polar King vessels.
RWE will now begin working towards commissioning the final 41 turbines of the 160-turbine project in 2015.
The first power from Gwynt y Mor was exported in August 2013 just three months after the first turbine was installed. RWE said all offshore construction has taken just under three years to complete.
The final Siemens 3.6MW turbine was installed in July 2014 and the developer since then has been installing the last of the cables.
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