Alan Pardew’s charges will now play Manchester United in the showpiece event in May after Connor Wickham’s second-half header downed the Hornets at Wembley on Sunday.
A towering second-half header from Connor Wickham proved decisive as Crystal Palace booked their place in the FA Cup final with a 2-1 win over Watford in the last four at Wembley.
The Eagles will now go on to play Manchester United, who beat Everton in the other semi-final, in May in a repeat of the 1990 FA Cup final between the two sides.
Palace took the lead after just six minutes through Yannick Bolasie, who stabbed home from close range after Damien Delaney flicked on a Yohan Cabaye corner.
Watford levelled shortly after the break through Troy Deeney, before Wickham went up the other end six minutes later and beat past Costel Pantilimon with a sublime header.