The Hornets will be hoping it signals an upturn in fortunes for the side which was in third place two months ago but which has taken just nine points from the previous 36 available before they took on the Canaries.
It was a disappointing afternoon for Norwich who at times played the better football in the first half but were generally outfought by a Watford side that simply was more determined.
Norwich made the early running with David Nielsen heading Mark Rivers' centre across the face of the goal.
Alec Chamberlain then had to block at the near post as Nielsen looked to shoot.
Watford tried to get into the game but failed to seriously threaten the visitors goal and again Norwich went close when Phil Mulryne headed a Darel Russell cross against the post.
Watford took the lead two minutes before the interval when Jermaine Pennant centred and Micah Hyde set up Allan Nielsen for a low drive into the net.
Seven minutes after the break Norwich were gifted a goal when a cross by Mulryne was challenged for by Iwan Roberts who attempted to flick it goalwards but the ball continued on its path wide of the goal only to strike Watford skipper Neil Cox on the knee and deflect inside the post.
Norwich failed to build on this and instead it was Watford who finished the stronger of the two teams.
Heidar Helguson sent a header straight at the keeper when meeting a cross from the right-hand side and then after a neat exchange with Tommy Smith he worked an opening but sent his shot into the arms of the well-positioned Robert Green.
Green then saved a shot from Smith but four minutes before the final whistle Watford grabbed the winner when Anthony McNamee's corner was met with a powerful ten-yard header by Helguson.