The dying embers of Albion's play-off hopes were finally extinguished despite a gallant second-half comeback against the Hornets.
The visitors had cruised into a 2-0 lead thanks to Sean Murray's free-kick and a Troy Deeney penalty, but Gus Poyet's side were resurgent after the break, netting through stand-in skipper Inigo Calderon and Will Buckley - against his former club.
The point curbed a three-game losing streak for Albion and the performance was a marked improvement on Saturday's 6-0 defeat at West Ham.
Indeed, Albion were looking to make immediate amends after the trip to Upton Park but debutant David Gonzalez - in goal as a replacement for Peter Brezovan - was picking the ball out of his net after just six minutes as Murray fired home a 25-yard free-kick.
Given recent results, there was a subdued atmosphere inside the Amex but it livened up when John Eustace appeared to raise his arm in the direction of Ashley Barnes' face, but received only a caution from referee Scott Mathieson.
Buckley had a good chance to get&nbsp;the Seagulls&nbsp;back on level terms after 19 minutes when he latched onto a Barnes pass, but his close-range effort was beaten out by Hornets keeper Tomasz Kuszczak.
Kazenga LuaLua, one of five changes made by Poyet from Saturday, also saw a low drive fly narrowly wide as Albion upped the ante.
Gonzalez held a spectacular overhead volley from Deeney, but it was Albion who again went close on 36 minutes, when Calderon's cross was only half cleared by the Hornets rearguard. The ball fell to Barnes on the edge of the box but his first-time volley flashed the wrong side of the post.
Buckley was again foiled five minutes before half-time, when he connected with a Marcos Painter cross, but his header came back off the woodwork and into the grateful hands of Kuszczak.
The night went from bad to worse a minute before the break when Barnes was adjudged to have brought down Jonathan Hogg, and Deeney made no mistake from the spot.
Albion were handed a lifeline ten minutes after the re-start when Calderon - wearing the armband in place of the rested Gordon Greer - saw his fierce drive beaten out by Kuszczak, but the Spaniard made no mistake with his follow-up.
The arrival of Vicente followed soon after, as a replacement for LuaLua, as Albion upped their game in search of the equaliser.
It duly arrived 11 minutes before the end when Vicente's low cross from the left was turned home first time by Buckley - his eighth goal in 14 league starts.
With five minutes of injury time Albion went in search of the equaliser but Vicente saw a last-gasp effort again beaten out by Kuszczak.
Albion: (4-4-2) Gonzalez; Calderon, El-Abd, Dunk, Painter (Vincelot 46); Buckley, Bridcutt, Dicker, LuaLua (Vicente 58); Barnes, Mackail-Smith. Subs not used: Ankergren (GK), Assulin, Noone.
Watford: (4-4-2) Kuszczak; Doyley, Nosworthy, Taylor, Dickinson; Murray, Buaben (Assombalonga 90), Eustace, Hogg; Iwelumo (Garner 84), Deeney. Subs not used: Loach (GK), Bennett, Whichelow.
Referee: Scott Mathieson
Yellow Cards: LuaLua, El-Abd (Albion); Eustace, Dickinson, Doyley (Watford)
Attendance: 19,189 (1,192 Watford)