Steve Morison kept his cool to conjure up a 49th-minute winner as Millwall made it a magic nine points out of nine with a third successive win at the Withdean Stadium.
Lions striker Morison capitalised on a defensive howler by Adam Virgo four minutes after the restart, rounded keeper Michel Kuipers and calmly slotted home his 11th goal of an increasingly productive season.
Following last year's thumping 4-1 defeat on the south coast Millwall were not only determined to gain revenge for that loss, but to also keep the momentum going following victories against Oldham Athletic (1-0) and Southend United (2-0) in the past week.
Brighton, who had not tasted victory on home soil since 30th October, have proved to be something of a bogey side for the south Londoners in recent seasons and were clearly charged up for this encounter - so much so that Tommy Elphick was booked after just two minutes and 48 seconds for a shuddering challenge on Shaun Batt.
The Seagulls and Lions swapped chances in the first 45 minutes; Chris Hackett's low drive was held by keeper Kuipers on eight minutes whilst Inigo Calderon saw his 20-yard angled free-kick fizz a foot wide in reply three minutes later.
Brighton went close again in the 25th-minute when Hackett gave away possession cheaply 22 yards out, Alan Navarro nipped in and let fly with a fierce drive that flew narrowly over.
Batt, on target for The Lions against Southend United on Tuesday, could have made it two goals in as many starts just past the half-hour mark, but was thwarted by Kuipers in the home goal from a good position.
At the other end visiting keeper David Forde produced his first real save of the half just before the break with a smart stop to deny Nicky Forster.
Brighton introduced Dean Cox for the injured Navarro after the restart, but the diminutive little midfielder barely had time to settle into his stride before Jackett's men had forged ahead.
There seemed to be no danger for home defender Virgo on the edge of his area, but he dwardled on the ball, Morison was quick to react and the Lions striker showed great composure to round onrushing keeping Kuipers before calmly despatching the ball into the back of the net.
Brighton were inches away from levelling straight from the restart when Nicky Forster hit a stinging effort over the bar with the visiting defence caught napping.
But that lapse in concentration was a rarity, and with Paul Robinson and Darren Ward in commanding form in the heart of the back four, supported by the commendable efforts of Tony Craig, Jack Smith and then sub Alan Dunne, The Lions were in no mood to relinquish their lead.
Hackett was on hand to head an 82nd-minute effort from Elphick over the bar and Glenn Murray's glancing header clipped the foot of the post (87mins) as Brighton pressed on in search of that elusive equaliser.
But it was Millwall who could have madxe the game safe with Batt twice spurning chances in one-on-one situations with Kuipers in the dying minutes.
Seconds after Murray had been denied by the woodwork, a quick break starting with Forde's long throw to Morison ended with Batt's effort from 12 yards being blocked by Kuipers at point-blank range.
Then in the second of four added on minutes, Batt was played through by a long Liam Trotter ball. However on this occasion he perhaps took one touch too many and the keeper again denied him with a smart block.
As The Seagulls launched one last attack Craig produced an outstanding challenge and did just enough to put off Cox as he prepared to pull the trigger from eight yards.
With that went Brighton's last chance of salvaging a point as Millwall marched on to a most welcome third successive win and clean sheet too.
Brighton & HA: Kuipers, Elphick, Navarro (Cox, 46mins), Forster (Dickinson, 64mins), Murray, Dicker, Colderon, Crofts, Painter (Holroyd, 64mins), Virgo, Bennett. Subs not used: Tunnicliffe, Carole, Hoyte, Brezovan.
Bookings: Elphick (2mins), Calderon (75mins)
Millwall: Forde, Smith (Dunne, 73mins), Craig, Abdou, Robinson, Ward, Martin (Barron, 82mins), Trotter, Morison, Batt, Hackett. Subs not used: Sullivan, Price, Laird, Harris, Grabban.
Bookings: Abdou (21mins), Craig (79mins)
Scorer: Morison (49mins)
Ref: Kevin Friend
Att: 6,610 (away 829)