Hull suffered a sixth straight loss in the Premier League as a late Michael Dawson own goal handed Watford a 1-0 victory on Saturday.
It was a cruel loss for Hull, who rarely shone in attack, but had looked resolute in defence before Dawson inadvertently turned the ball into his own net in the 82nd minute.
Watford attacked in waves down the right through Nordin Amrabat, but it was the returning Daryl Janmaat who sent in the cross which led to the winner.
Victory means Watford have picked up eight points in their last four league games, while Hull remain in the relegation zone.
In the first ever top-flight meeting between the two sides, captain Troy Deeney was searching for a 100th Watford goal, having scored against Hull on the last three occasions.
And Deeney almost gave Watford the lead from kick-off, but he was inches away from meeting Amrabat's cross.
The hosts continued to threaten and hit the woodwork twice in quick succession after just five minutes.
The first came from a corner as Younes Kaboul saw his header cannon off the crossbar, with Hull failing to clear their lines after.
The ball eventually fell to Roberto Pereyra, but his curled effort from distance flicked the outside of the post with David Marshall beaten.
Watford failed to make their early pressure count as the pace of the game dropped, while Hull did not create any telling chances in the first half.
Just before the break, Amrabat hit a half-volley into the ground and it bounced over to Deeney at the far post, but the Watford captain could only head wide.
Hull's greatest chance of the game fell five minutes into the second half, with Abel Hernandez latching onto a Will Keane flick-on, but the striker could only shoot straight at Heurelho Gomes.
Time and time again Amrabat threatened down the right, constantly getting the better of Sam Clucas, but the final ball was often lacking from the Dutch winger.
Instead, it was Janmaat's cross which led to the goal, with the ball ricocheting off Dawson - and the Hull captain could only watch on as it sailed beyond the helpless Marshall.
Watford could have doubled their advantage with three minutes to go, but Odion Ighalo shot narrowly wide after working his way into a shooting position.
The loss leaves Hull without a league win since August 20, while Watford move up to seventh in the table.
Player ratings
Watford: Gomes 6, Kaboul 6, Prodl 7, Britos 6, Amrabat 7, Pereyra 6, Behrami 5, Capoue 7, Holebas 6, Deeney 7, Ighalo 7.
Subs used: Janmaat 7, Kabasele N/A, Zuniga N/A.
Hull: Marshall 6, Davies 7, Maguire 6, Dawson 7, Elmohamady 6, Clucas 5, Henriksen 5, Mason 6, Livermore 6, Keane 6, Hernandez 5.
Subs used: Meyler 6, Bowen 6.
Man of the match: Nordin Amrabat.