The defender, 27, has secured a return to the Premier League after joining the Hornets on a four-year deal for a fee believed to be in the region of £7.5 million.
Watford has completed the signing of Netherlands international defender Daryl Janmaat from Newcastle United on a four-year deal.
The financial terms of the transfer were not disclosed, with Watford reported to have agreed a fee in the region of 7.5 million pounds ($9.9M) for the 27-year-old right back.
Janmaat has been capped 27 times by his country and joined Newcastle from Feyenoord in July 2014.