Daniel Tozser’s free-kick eight minutes into the second half looked to have put the high-flying Hornets on course for a fifth win in six unbeaten games at home this season, but they were pegged back when Lewis Dunk headed home from a corner 13 minutes from time.
Both sides looked to play their possession-based game from the outset, with Watford having to be patient early on as their opponents had greater control of the ball.
The Hornets increasingly came into the game but chances were few and far between in the opening 30 minutes as the game continued to be something of a chess match.
Chris O’Grady warmed Heurelho Gomes’ gloves with a low strike from the left side of the area early on and later saw another effort deflected through to the Hornets’ goalkeeper.
In between, Andrew Crofts had seen a couple of attempts go wide, while at the other end David Stockdale had to leap to hold a Gianni Munari header beneath his crossbar from Watford’s first corner of the afternoon.
The hosts continued to get in the more promising attacking positions, only to be let down too frequently by the quality of the final pass.
But the Hornets almost got it right three minutes before the break when, after an Ikechi Anya header near his own penalty area had set his side away on the counter-attack, Juan Carlos Paredes slipped the ball to Matej Vydra, who spun after taking a touch but lifted his attempted finish over the crossbar.
Watford only had eight minutes of the second half to wait before making the breakthrough though, as Bruno’s trip on Almen Abdi 25 yards was doubly punished after the Brighton defender had been cautioned.
Tozser took the free-kick and although his left-footed effort was struck well enough, the Brighton wall parted alarmingly to leave Stockdale rooted to the spot as the Hungarian gave his side the lead.
Sami Hyypia made two changes after seeing his side go behind, bringing on the more attack-minded Kazenga LuaLua and Danny Holla, but his side still struggled to create any opportunities of note.
But they were nearly handed a route back into the contest when LuaLua sent in a dangerous low cross from the right and Joel Ekstrand diverted it narrowly wide of his own goal.
The visitors were starting to ask questions from set-pieces though, and after Dunk and O’Grady had seen headers miss the target from corners, their efforts were to be rewarded when Dunk got free at the near post to plant a header from LuaLua’s corner from the left beyond Gomes in the 77th minute.
But the Hornets could have won it with two minutes remaining when a fine Lewis McGugan pass released Vydra but his first-time left-footed strike was well saved by Stockdale.