Ashley Young's 12th goal of the campaign had given Watford a slender lead at the break, but they really turned the screw in the second half and the Sky Blues were blown away by wave after wave of yellow shirted attacks.
But the game was again proof that if a team doesn't take its chances it doesn't deserve to win because Coventry should have been in front after 16 minutes.
A Dennis Wise shot broke for top scorer Gary McSheffrey in the penalty area and he held of Jay DeMerit to create a chance but was denied by a Ben Foster block.
Watford though had dominated the first half and made it count just after the half-hour when Young attacked a Matthew Spring cross from the left at the near post and clipped the ball over Marton Fulop.
But it was in the second half that the Hornets showed the attacking flair that has brightened up the Championship this season, and it was no surprise when they added to their lead.
Young turned creator with a corner from the right and the division's leading marksman Marlon King met the set-piece with a thumping header.
Fulop did well to deny Young a third goal, but any hopes Coventry had of salvaging a point disappeared when sub Kevin Thornton broke through but couldn't find a way past Foster.
Any doubts about the outcome were put to bed soon after when some slack marking presented Darius Henderson with a straightforward header from a Young free-kick, and Watford followed that up with a quickfire fourth.
Coventry failed to clear their lines following another set-piece and the ball broke to Hameur Bouazza whose shot was parried out into the heart of the area by Fulop, leaving DeMerit with an easy header.