RWE's jack-up installation vessel, Friedrich Ernestine, completed the installing the 160th foundation on Wednesday 23 April.
The ship will now travel to the Nordsee Ost project to install its turbines in the German North Sea.
The £2 billion (EUR 2.4 billion) project remains on course to be completed by the end of the year to become the world's second largest offshore wind farm behind the 630MW London Array.
Installation of the monopiles and transitions pieces for the 160 Siemens 3.6MW turbines began in August 2012.
Gwynt y Môr is owned by German developer RWE Innogy (60%), energy supplier Stadtwerke München (30%) and technology giant Siemens (10%).