Following a tense 120 minutes in which neither team could break the deadlock, Solly March skied his penalty to present Victor Lindelof with the opportunity to take the Red Devils to their second domestic final of the season, which he took.
March was the only player to miss out of the fourteen spot-kick takers, in what was near-perfect demonstration of how to take penalties under pressure.
United will now face Manchester City in the final on June 3, while Brighton will now have nine league games to try and cement a place in a European competition next season.
The result means the Red Devils can put Thursday’s disappointing exit from the Europa League behind them and look forward to a potential second trophy entering the cabinet at the end of the season.
Despite having less of the ball in the first half, United had the best chances, in what was an intriguing game throughout. Fernandes saw one effort well-saved and another pulled just wide of the post.
Brighton built up well from the back with a number of slick passing moves, but lacked a killer final pass. Alexis Mac Allister had a free-kick tipped round the post by De Gea, in what was Albion best chance in the early exchanges.
HAVE YOU READ THIS?
The second half was just as edgy as the first, with few clear cut chances for either side. Enciso had a half volley tipped over the bar by De Gea from 12 yards out, with the resulting corner seeing Welbeck head wide at the back post unmarked, when he should have scored.
In extra time, Robert Sanchez brilliantly stopped Rashford’s curling effort to keep the game at 0-0, while a heavy touch let Karou Mitoma down as he was bearing down on David De Gea’s goal, as penalties loomed ever closer.
Having already lost one shootout this season to Charlton in the EFL Cup, in which March also missed by firing his penalty over the bar, Brighton managed to score all their first six penalties with ease.
Having gone 5-4 ahead, Sanchez will have been disappointed not to have saved Sabritzer’s deciding kick, as he watched the ball squirm through his hands and into the net.
But March’s miss means Brighton’s wait for a second FA Cup final appearance continues though, here are the Brighton player ratings from today’s game.
5. Pervis Estupinan - 5/10
Looked slightly rushed when in possession of the ball. Gave it away cheaply a number of times and was caught out once or twice by the pace and trickery of Antony. Nevertheless, took his penalty well and sent De Gea the wrong way. Photo: GLYN KIRK
6. Alexis Mac Allister - 6/10
Struggled to impose himself on the game, being asked to return to his former, deeper role alongside Caicedo. Still looked calm and composed when in possession and played better when he was moved into the number 10 role in the second half. Took his penalty well. Photo: Matthew Peters
7. Moises Caicedo - 9/10
A classy performance from the young midfielder. covered a lot of ground, looked great on the ball and carried it forward into dangerous positions a number of times. Won the battle against Casemiro . Photo: Mike Hewitt
8. Solly March - 6/10
Lacked any end product, having got himself into a number of good positions following some good work with the likes of Mac Allister and Gross. Did well to create his second half chance all on his own. Nothing but sympathy for the penalty miss through, a carbon copy of the one he took against Charlton earlier this season. Photo: Mike Hewitt