Forsyth made his Dundee debut five years ago, aged 17
Watford have signed Dundee midfielder Craig Forsyth on a three-year contract for an undisclosed fee, plus add-ons.
Since debuting for Dundee in November 2006 the 22-year-old has made 69 appearances, scoring 13 goals.
Former Hornets boss Malky Mackay had rubber-stamped the move for the left-sided player before he departed for Cardiff last week.
Forsyth, who has had loan spells at Montrose and Arbroath, featured 35 times for the Dee last term.
It was his most fruitful season in front of goal, finding the net on eight occasions.
The transfer fee could rise if the midfielder makes an unspecified number of appearances for the Hornets.