Leeds went ahead in the 20th minute through Daniel James who took advantage of a terrible back pass from Edo Kayembe and James doubled the Whites advantage when finishing off a clinical counter eight minutes later.
A deflected Manor Solomon strike then put Leeds 3-0 up by the interval and a fourth goal arrived just after the hour mark through Joel Piroe after fantastic work from Ao Tanaka who ran in a circle to skin Tom Ince on the edge of the box.
Victory for Daniel Farke's side established a five-point advantage back to second-placed Sheffield United but also built a new eight-point cushion in the automatic promotion places back to third placed Burnley, albeit the Blades and Clarets have a game in hand.
Graham Smyth, the YEP’s chief football writer, hands out the scores from a rampant Whites display in the Tuesday night clash at Vicarage Road.
1. Illan Meslier
8 - Another game in which he was largely a spectator but stayed alert and made two important stops, one in each half. Distribution was fine too. Photo: Richard Heathcote
2. Jayden Bogle
8 - Wanted to get at Watford on the right but had to do some defending in the first half and did it well. Worked hard in the second half, made some great runs. Photo: Zac Goodwin
3. Joe Rodon
9 - So solid in both halves, with big headers, clearances and progressing the ball nicely. Photo: Richard Heathcote
4. Ethan Ampadu
8 - Wasn't flawless but was pretty good all the same. Some nice passing from the back. Photo: Richard Heathcote
5. Junior Firpo
8 - He and Solomon weren't always on the same page but his runs and movement were good. Got involved in attacks, got back and defended. One second half dribble was ill-advised. Photo: Zac Goodwin
6. Ilia Gruev
8 - Covered a huge distance again. Some really tidy work on the ball. Helped control Watford even if the hosts had the ball. Set-pieces were a mixed bag. Photo: Zac Goodwin