Danielle van de Donk scored a hat-trick as Arsenal, down to 10 players for much of the game, crushed Sunderland to reach their 15th Women's FA Cup final.
The Gunners lost Emma Mitchell to two yellow cards, but Van de Donk and Dan Carter put them in control.
Sunderland's Abby Holmes was then sent off for fouling Carter in the box, with Fara Williams converting from the spot.
Van de Donk went on to complete her treble, with Carter adding a second and Jordan Nobbs also on target.
Arsenal, who have won the FA Cup a record 13 times, remain on course to lift the trophy for a third time in four seasons.
They will face Chelsea in the final at Wembley on 14 May after the Blues beat Manchester City 2-1 after extra time in the other semi-final.
Arsenal captain Casey Stoney:
"Normally you go down to 10 and you panic, but we didn't. We knew we were good enough and we knew we could move the ball.
"Everything just clicked. We've been looking for a performance like that for a while. I'm sure Sunderland will be very disappointed, but they'll learn from it and we move on to the final.
"Wembley is one of the most exciting things. You dream of playing there as a young girl and now we're there.
"We knew we had to win to do that, but now it's not just about going to Wembley. It's about going there and picking up a trophy."
Sunderland manager Carlton Fairweather:
"Credit to Arsenal. They worked very hard despite being down to 10 players. They're a really good side.
"We always knew that anyway and, for some reason, we thought the game was over when they went down to 10.
"Obviously that has come back to bite us on the backside. It's a massive confidence blow and it does feel devastating.
"We finished better than last year but obviously it's disappointing what we've done."
Arsenal: Van Veenendaal, Mitchell, Stoney, Losada, Natalia (Smith 78), Nobbs, Carter, Corredera (Williams 60), Janssen, Rose, Van de Donk.
Subs not used: Byrne, Williamson, McCabe.
Sent off: Mitchell (33)
Sunderland: Laws, Holmes, Furness (McDougall 82), Bannon, Mead, Johnston (Ramshaw 64), Joice (Kelly 56), Chaplen, Williams, Sjoman, Staniforth.
Subs not used: Sharp, Olsen.
Sent off: Holmes (72)