"Netherlands international Daryl Janmaat has joined the Hornets in a permanent transfer from Newcastle United, Watford FC is pleased to confirm," Watford said in a statement on its website.
"The 27-year-old, who plays in the right wing-back position, has signed a four-year contract at Vicarage Road."
Janmaat, who has 27 caps for his country, made 32 league appearances last season but could not help Newcastle avoid relegation from England's top flight.
Watford, who have started their league campaign with one point from the opening two games, host Arsenal on Saturday.
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(Reporting by Ian Rodricks in Bengaluru; editing by Mark Heinrich)
