Albion claimed the title of undisputed champions in a perfect climax to their home campaign.
They won the clash of the Third Division heavyweights with a knockout blow landed by Danny Cullip.
His towering header 11 minutes from the final bell carried the Seagulls five points clear of their promoted victims, who have only one match left at home to Halifax on Saturday.
Chesterfield, up despite their defeat as a consequence of Hull's failure to win at Southend, will drop a further nine points adrift of Micky Adams' all-conquering heroes tomorrow.
That is when the Football League Board is expected to ratify yesterday's re-confirmed verdict of the disciplinary panel which examined the financial indiscretions of the trouble-torn Derbyshire club.
The ghastly mess, branded a "farce" by Adams, meant League sponsors Nationwide had to mount cloak and dagger plans for a trophy ceremony.
The podium was hidden underneath a blue tarpaulin behind the west goal at Withdean.
The presentation of the silverware and medals to Adams and his players would never have taken place had they not secured the win they needed to finish above Chesterfield irrespective of the points punishment.
Fans in another packed and vocal crowd only found out via a somewhat premature announcement over the tannoy once Cullip had powered Albion ahead.
They were in no mood to showed any mercy to the Chesterfield players. A gigantic brown envelope was passed around the south stand.
Much to Adams' dismay, the visitors' warm-up was accompanied by a song entitled "I'm The Taxman".
Chesterfield boss Nicky Law missed the match to attend the club's disciplinary hearing in Leeds, but his team did not need motivating after that.
Nor, for that matter, did Albion. There was a score to settle following the controversial 1-0 defeat at Saltergate in October, in which Chesterfield players were accused of getting Charlie Oatway sent off.
Premiership referee Steve Bennett was predictably busy in a tight and frenetic first half, when chances were few and far between.
Oatway, Paul Watson, plus three opponents were booked in the opening 45 minutes.
Bobby Zamora, named player of the season by both the supporters and the Seagulls Club for juniors, attracted big-name attention yet again.
Middlesbrough were represented and Charlton boss Alan Curbishley, who brings his side to Withdean next Tuesday for a benefit match on behalf of physio Malcolm Stuart and retired kit man Jock Riddell, was there as well.
The former Albion midfielder's hopes of keeping a low profile were well and truly destroyed when he was interviewed beside the pitch at half time!
Zamora had the best effort of the first half. He checked inside from Gary Hart's diagonal pass to strike a wicked left-foot shot which was beaten away by the impressive Mike Pollitt.
Early in the second half Zamora was too high with a free header from Kerry Mayo's left-wing cross.
It was the sort of chance he has gobbled up on his way to 31 goals this season and you began to wonder whether Albion would break Chesterfield's well-organised and robust resistance.
The visitors' ambition was limited to the point they required at the start of play to clinch promotion.
They only seriously threatened once, when Jon Howard capped a swift counter-attack and solo run with a low drive narrowly wide.
The shots on target count of 7-0 in the Seagulls' favour reflected the pattern of play.
Finding a way past the want-away Pollitt was the problem, as Mayo discovered when the keeper dived to parry a fine effort by Albion's leftback for a corner.
Another corner a few minutes later produced the moment everybody had been waiting for.
Watson delivered it with customary accuracy to the unmarked Danny Cullip, whose thunderous header found the roof of the net.
Cullip was another appropriate matchwinner after Zamora's hat-trick against Macclesfield last Saturday saw Albion unofficially crowned as champions.
The dependable central defender was the Seagulls' other representative in the PFA's Third Division team of the season, which just goes to show how highly he is regarded by his fellow pros as well as Adams.
The 700 or so Chesterfield supporters, tucked away in the north-east corner, found their voices in the closing stages as news filtered through that Hull had been held.
But that was nothing to the crescendo of noise which greeted the Albion players and staff as they re-emerged a few minutes after the final whistle to collect their medals and first trophy for the club since 1965.
It was truly a night to cherish.
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