Apart from the wider margin of victory their performance deserved, all that was missing for Watford was a goal for record signing Nathan Ellington - but he so nearly got it.
Ellington was introduced with 17 minutes remaining and beat Neil Alexander with a shot from the right side of the area, only to see it cannon away off the inside of the post.
That would have been the icing on the cake after the Hornets took a grip from their first attempt after six minutes.
Jordan Stewart's measured pass down the left found Lee Williamson, who had crept in unnoticed behind the Tractor Boys defence, and he nodded the ball back to Darius Henderson, who struck a powerful half-volley into the ground and through Alexander's legs.
That was the catalyst for the Hornets to go and control the opening 45 minutes but without managing to score the second their play deserved, although Henderson twice should have done better from close range.
Ipswich came more into the game after the break and had some decent spells of possession, but, crucially were unable to force Mart Poom into a save.
Watford, without looking as assured as they had done in the first period, always looked the more likely scorers of a second goal and so it proved after Henderson and Jobi McAnuff had gone close to extending the home side's advantage.
Moments after Ellington had replaced Henderson to make his Watford debut, Tommy Smith received the ball wide on the right and cut inside before unleashing a superb left-footed curling shot from 25 yards that flew past Alexander.