Things started out promising for Spurs, who went up just 11 minutes on a Dele Alli goal.
But an equalizer 13 minutes later from Alexis Sanchez got the Red Devils on level terms, and Ander Herrera’s second-half winner saw the Red Devils come away with the victory and a trip to the final where they will face either Chelsea or Southampton on May 19.
It guarantees another season without silverware for Spurs and yet another season in which they have stumbled in the FA Cup semi-finals. Tottenham have now fallen a record eighth straight time upon reaching the penultimate round, with their last successful run to the tournament final coming in 1991.
That was also the last time Spurs won the FA Cup.
The loss also continued an odd trend for Mauricio Pochettino's men in knockout competitions. The club have been bounced from the Carabao Cup, Champions League and now the FA Cup this season. In all three, Tottenham found themselves in winning positions.
Spurs were up 2-0 against West Ham, before a furious comeback by their London rivals saw the Hammers emerge 3-2 winners. In the Champions League, they were up 1-0 in the second leg against Juventus and 3-2 on aggregate, before a pair of goals saw the Serie A side emerge triumphant 4-3.
Incredibly, the losses to West Ham and Juventus both came at Wembley Stadium as well, meaning Spurs were eliminated from all three competitions in their current home stadium, though the FA Cup loss is not technically a home match.
To add to the oddity, the London side have not lost a single game this season from a winning position in the Premier League.
Tottenham will have time to lick their wounds as they next take the field on April 30, when look to ensure a top four Premier League finish as they battle Watford at Wembley.