Extra-time efforts from James Tilley, Richie Towell and Joe Ward helped Albion secure a 3-0 final success over League 2 outfit Crawley Town at the Amex.
The final was far from a thriller but Brighton's young guns pulled away after it ended all square following 90 minutes.
Both Tilley and man-of-the-match Forbes had chances to wrap it up in normal time, before Albion did run out winners in extra-time.
Tilley broke the deadlock after 102 minutes, then Towell and Ward notched in the second half of extra-time to ensure Brighton won the Sussex Senior Cup for a 14th time.
Albion stopper Robert Sanchez was the first goalkeeper called into action after four minutes. Crawley forward Rhys Murphy cleverly spun his man, before firing an effort which was dealt with by Sanchez low to his right.
Brighton then went close through Richie Towell three minutes later. Tyler Forbes' persistence down the right saw him work some room, he then picked out Towell but he flashed a strike across goal.
James Tilley then got in behind Crawley's midfield with 13 minutes gone, though, his fierce drive went just over.
Albion were looking the more likely as the half went on and Tom Dallison's poked an effort back across goal on the half-hour. The central defender met George Cox's corner, getting the better of opposite number Josh Yorweth, but could only flash across the face at full stretch.
Crawley conceded a flurry of free-kicks on the edge of their area just prior to the break and they were nearly punished on 44 minutes. Tilley's left-foot curler looked destined for the top corner, only for his strike to ruffle the side-netting.
Just as in the opening 45 minutes, Albion 'keeper Sanchez was forced into an early stop in the second. The ball fell kindly for Murphy less than two minutes after the restart but his snapshot half-volley was straight at Sanchez.
Forbes was being allowed acres of room down the right and he fired in a teasing cross on the hour. His pick out fizzed across goal and just out of Tilley's path.
The dangerous Forbes continued to cause problems, this time he cutback onto his left-foot, firing in a cross which Towell could only flick over with his head six minutes later.
Albion were seeing alot of the ball and skipper Dessie Hutchinson tested Yusuf Mersin 15 minutes from the end. Tilley showed good strength on the edge, before teeing up Hutchinson whose side-foot strike was straight at Mersin.
All good things for Brighton seemed to be coming from Forbes and he had a great chance eight minutes from time. Great link-up down the right between Forbes and Joe Ward saw the former played through but he failed to test Mersin.
Tilley was then gifted a chance to win it for Brighton four minutes later. Mersin made a hash of a clearance with the ball falling to Tilley, only for Crawley's goalkeeper to recover and parry his effort wide.
Substitute Enzio Boldewijn so nearly won it for Crawley two minutes into stoppage-time but Forbes made a cracking recovery tackle as the match went to extra-time.
The deadlock was finally broken seven minutes into the first half of extra-time. Forbes' superb cross picked out Tilley, who fired a first-time volley past Mersin.
Boldewijn showed great strength, holding off Cox, but his drive went just wide of the post on 102 minutes as Crawley looked for a way back in.
Brighton then had things all but sewn up seven minutes into the second half of extra-time. Confusion between Yorweth and Mersin allowed Towell to nip in, round Crawley's goalkeeper and slot into an empty net.
Towell then turned provider as Albion wrapped it up three minutes later. The scoring of the second goal teed up Ward to thunder home as Brighton were crowned 2017 champions.
BRIGHTON U23s: Sanchez; White, Hall, Dallison, Cox; Forbes, Hutchinson, Molumby, Ward; Towell; Tilley. Subs: Collings, Barclay (Molumby, 104), Davies (Hall, 72), Collar, Mandriou.
CRAWLEY: Mersin; Lelan, Garnett, Yorweth, Blackman; Clifford, Tajbakhsh; Bawling, Murphy, Roberts; Harrold. Subs: Morris, Young, Payne (Tajbakhsh, 63), Boldewijn (Bawling, 72), McNerney (Garnett, 72).