With both sides having little to play for, the match rarely sparked into life and Alhassan Bougherra's close-range shot was Watford's best chance.
But for Stuart Green's fierce 20-yard shot, Hull hardly threatened at the other end in a dour encounter.
The tempo increased in the second half, but the poor quality ensured both teams ended the season with a whimper.
Watford top-scorer Marlon King threatened on two occasions on his return to the line-up, while Chris Eagles could have opened the scoring in the first half with a close-range shot.
Keith Andrews' introduction gave Hull some inspiration, but the Tigers failed to trouble Ben Foster in the Watford goal.
Adrian Boothroyd's men now take a five-match unbeaten run into the play-offs.
Crystal Palace's defeat at Sheffield United means the Hornets will face Iain Dowie's men in the play-off semi-finals with the first leg at Selhurst Park on 6 May and the return leg three days later.
In the other tie, Preston will meet Leeds with the Yorkshire side at home on 5 May and at Deepdale on 8 May.
Watford manager Adrian Boothroyd:
"Crystal Palace are definitely the favourites, they have a top manager, a big, talented squad, and they have beaten us twice this season.
"I'm not too worried about our results against them earlier in the season, because we have improved since then.
"Our play-off rivals Palace, Preston and Leeds all have to carry expectation we don't have."
Hull manager Peter Taylor:
"I would back Crystal Palace for promotion, because of striker Andrew Johnson.
"If he sees that Michael Owen and Wayne Rooney are injured and could miss the World Cup, it will give him an extra spur to try to make the England squad.
"Watford are well-organised and very fit, but it might come down to who has the best forward."
Watford: Foster, Doyley, DeMerit, Mariappa, Stewart, Eagles, Mahon, Bangura, Young (McNamee 62), King, Henderson (Spring 81).
Subs Not Used: Chamberlain, Chambers, Robinson.
Hull: Myhill, Thelwell, Delaney, Cort, Rogers (Dawson 45), Green, Welsh, Andrews, Ellison (France 85), Fagan (Duffy 45), Parkin.
Subs Not Used: Duke, Paynter.
Ref: K Friend (Leicestershire).
Play-off semi-final dates:
Leeds v Preston
(Elland Road, Friday, 5 May, 1945 BST)
Crystal Palace v Watford
(Selhurst Park, Saturday, 6 May, 1215 BST)
Preston v Leeds
(Deepdale, Monday, 8 May, 1945 BST)
Watford v Crystal Palace
(Vicarage Road, Tuesday 9 May, 1945 BST)
Play-off dates for other divisions to be confirmed