The resounding victory was the hosts' biggest of the season and only their first home win of 2022, having only picked up four points from their previous eight games at the Amex.
Dunk said he was 'buzzing' after the game, adding: "It's a nice feeling.
"It's nice to reward the home fans with something. We've had some not-so-good performances this season.
2Our away form has been better than home. For a game to come together like that, against a Man United team is unbelievable and we enjoyed it.
"In the Premier League, it's one of the best as a team performance. From the first minute to the last, we were better team. We didn't let them have a sniff really.
"That felt nice, two clean sheets in a row."
Dunk said Albion had a 'game plan to attack them, get in their faces and make it hard for them'.
"We did that," he said. "We played on the ball excellently, especially in the second half. It's probably the best we've played.
"As a centre-half it was weird to get to the end of the game, not panicking and not heading a thousand balls out the box. It was nice to be comfortable and hopefully we can carry that on in the last two games."
Dunk admitted he 'of course' took extra pleasure from keeping Cristiano Ronaldo quiet.
He said: "He's one of the greatest ever to play the game.
"It's a challenge you relish before the game. You know you're in for a tough game.
"At their place, he scored and I didn't want to let him score today.
"Thankfully, as a team we didn't let them score. It's nice to challenge yourself against the best players.
"I think we dominated throughout the game.
"We've been waiting for one of these games to come all season. We showed what we were about."
Looking ahead to next season, Dunk said Albion have 'got more than enough' to challenge higher in the table, as long as they keep the squad together.
"We are in a good place," he said.
"We want to keep our squad together and maybe improve it. Let's see what happens in the summer.
"We know we are more than capable to keep pushing on each year. You are not going to win every game and you have to stick together in the tough times.
"We did that and got out the end of it. We all get on well together and are on the same journey."