Substitute Jesse Lingard thundered in an extra-time winner as 10-man Manchester United lifted the FA Cup for the record-equalling 12th time in their history.
Crystal Palace led for three minutes but Juan Mata cancelled out Jason Puncheon’s 78th-minute opener.
When Chris Smalling was sent off for a second bookable offence at the end of the first period of extra-time it looked as though it might be Palace’s day for the first time in their history.
But Lingard, who joined the Manchester United academy at the age of seven and lifted the FA Youth Cup in 2011, had his crowning moment in the 110th minute to earn the club a first trophy under manager Louis van Gaal.
Though United are no strangers to Cup Final day – only Arsenal had lifted the trophy more often – their players certainly are, with the last of their traditional open-top bus victory parades in 2004.
The magnitude of the occasion was certainly not lost on the Crystal Palace players either. Midfielder Wilfried Zaha was reduced to tears when he walked around the Wembley Stadium pitch pre-match.
With noise levels cranked up to maximum level it was Van Gaal’s side who settled quickest.
Marouane Fellaini went closest to opening the scoring after 10 minutes, but headed wide after climbing above Mile Jedinak.
Wayne Rooney, playing in a central midfield role, saw a deflected strike from 25 yards well held by Wayne Hennessey.
With Rooney soon on the rampage again Yohan Cabaye tracked back to break up play and Palace were able to break on the left flank with Connor Wickham running shoulder-to-shoulder with Smalling, for which the United man was cautioned.
Wickham won a free-kick on the edge of the box which Cabaye whipped goalwards. It was met with a deft header at the near post from Yannick Bolaise, but David de Gea opted to push over the the crossbar.
In an end-to-end start Mata was next to go close. The only player in the United team with a Cup-winner’s medal profited when a poor clearance from Pape Soure fell his way, but the former Chelsea man’s low shot across goal was parried away by Hennessey.
Next the handling of De Gea was tested, Bolasie with a low effort from 20 yards bounced awkwardly in front of the Spain No1, though he held onto it with little fuss.
Marcus Rashford had the United fans out of their seats with a lung-busting run down the right flank, then crossed to Anthony Martial at the far post, but the Frenchman’s fierce, first-time effort was blocked by Joel Ward.
Just as in the first half, United came out of the traps quickest in the second and eight minutes after the restart the woodwork came to Palace’s aid.
Rashford, United’s most potent attacking weapon thus far, flicked an Antonio Valencia pass into the path of Fellaini, whose first-time effort from 12 yards cannoned back of the near post.
Jedinak found himself in space at the far post when a free-kick fell his way, but the Australia midfielder lashed high and wide.
The Palace goal was living a charmed life though and on 61 minutes Martial met Valencia’s clipped cross with a powerful header that bounced off the post and away to safety.
With 20 minutes remaining Rashford, when embarking on a typically penetrative run, slipped on the edge of the box and was inadvertently trodden on by Cabaye.
Despite treatment he limped off the field to be replaced by Ashley Young, who was immediately thrown into a central role, keeping Martial wide on the left.
United had controlled proceedings for much of the second period, dominating possession while Palace were forced to sit deep inside their own half, leaving Wickham with a challenging task at the top of the pitch.
But the introduction of substitute Puncheon gave the Eagles the spark they required and with 12 minutes remaining they took the lead.
A punt forwards from Ward fell to Puncheon on the left-hand side of the box and he thrashed a half-volley beyond De Gea to break the deadlock.
The goal was met with a jig of delight from Alan Pardew, but within three minutes his mood had changed as United levelled.
Rooney carried the ball purposely from left to right, crossed to the far post where Fellaini brought the ball down on his chest and Mata’s volley was too powerful for Ward to block on the line.
Deep into second-half stoppage time Zaha got the better of Smalling, but his right-footed drive swerved wide and into the side-netting.
In extra-time Rooney and Lingard shot harmlessly off target. But De Gea had to be sharp at the other end to push a well-struck volley from Bolasie round the post.
With the first period of extra time drawing toward a conclusion Smalling unceremoniously dragged Bolasie to the ground to half his momentum and was shown a second yellow card by referee Mark Clattenburg.
Palace, with a man advantage, were determined to take the game to United. Substitute Dwight Gayle nipped in between the Red Devils centre-backs to latch on to Bolasie’s pass, but his stab at goal was blocked by De Gea’s legs.
It was another substitute who has to have the final say though.
Moments after Lingard had crossed for Michael Carrick, who could only head wide, the 23-year-old took matters into his own hands.
Valencia’s low cross from the right was blocked by Damien Delaney but the loose ball sat up perfectly for Lingard to unleash a stunning volley that gave Hennessey no chance.
Crystal Palace (4-2-3-1): 13 Wayne Hennessey; 2 Joel Ward, 6 Scott Dann, 27 Damien Delaney, 23 Pape Soure; 15 Mile Jedinak (captain) 18 James McArthur; 11 Wilfried Zaha, 7 Yohan Cabaye, 10 Yannick Bolasie; 21 Connor Wickham.
Substitutes: 42 Jason Puncheon for Cabaye 72, 16 Dwight Gayle for Wickham 86, 3 Adrian Mariappa for Dann 90.
Substitutes not used: 1 Julian Speroni, 25 Emmanuel Adebayor, 26 Bakary Sako, 34 Martin Kelly.
Manager: Alan Pardew
Goal: Puncheon 78.
Bookings: Dann 47, Delaney 62, McArthur 108.
Manchester United (4-1-4-1): 1 David de Gea; 25 Antonio Valencia, 12 Chris Smalling, 17 Daley Blind, 5 Marcos Rojo; 16 Michael Carrick; 8 Juan Mata, 27 Marouane Fellaini, 10 Wayne Rooney (captain), 9 Anthony Martial; 39 Marcus Rashford.
Substitutes: 36 Matteo Darmian for Rojo 66, 18 Ashley Young for Rashford 72, 35 Jesse Lingard for Mata 90.
Substitutes not used: 20 Sergio Romero, 4 Phil Jones, 21 Ander Herrera, 28 Morgan Schneiderlin.
Manager: Louis Van Gaal
Goals: Mata 81, Lingard 110
Bookings: Smalling 19, Rojo 41, Mata 45, Rooney 87, Fellaini 101, Lingard 110.
Red card: Smalling 106.
Referee: Mark Clattenburg