Coventry's Elliott Ward nearly paid for his moment of indecision in the 19th minute when Marlon King dispossessed the centre-half. When King's shot was saved by keeper Andy Marshall, his follow up strike from close range rebounded off the woodwork.
Marshall was again the home team's saviour when Tommy Smith knocked over a right-wing cross which fell to John-Joe O'Toole and the midfielder's header from 6 yards forced a fantastic save from the keeper.
Sky Blues boss Iain Dowie was forced to bring on Arjan De Zeeuw in the 25th minute when Gary Borrowdale left the field on a stretcher following a collision inside the box.
The visitors made their chances count by taking the lead on the half-hour mark. Coventry's 19 year old defender Ben Turner slipped and King pounced to deliver a right-wing cross which fell to Adam Johnson. The on-loan Middlesbrough midfielder let fly with a superb 16-yard strike which gave the keeper no chance.
The Championship leaders doubled their advantage in the 42nd minute. King turned smartly inbetween two Coventry defenders to unleash a firm left-footed shot from close range.
Watford stretched their lead 50 seconds into the second-half when Gavin Mahon's pass was touched on by King to Darius Henderson and the striker's volley flew past the helpless Marshall.
The home team finally came close to scoring in the 55th minute when David McNamee's goal-bound header was cleared off the line by O'Toole.
Watford should have added a fourth when substitute Tamas Priskin broke clear but with only the keeper to beat, the Hungarian's low effort was saved by an overworked Marshall.