After finishing fifth in the League One table, the Black Cats beat Sheffield Wednesday 2-1 on aggregate in the playoff semi-finals to set up a showpiece event with Wycombe Wanderers in the capital.
Sunderland, who are looking to return to the Championship after four years in the third tier, have a poor record in the playoffs, failing to secure promotion in each of their last seven attempts over the last 35 years.
Speaking to Sports Mole ahead of the release of his autobiography 'Kicking Back' on May 17, Onuoha reflects on his own experience in the playoffs during his time at Queens Park Rangers when they won the 2013-14 final to secure promotion from the Championship.
When asked whether Sunderland will mentally prepare for this weekend's final differently in comparison to a regular league fixture, Onuoha said: "Yeah, I think so because you've played a lot of games to get this opportunity. Obviously, you would have wanted to go up automatically, but this is the next chance".
"I've only played at Wembley once (for QPR). After we beat Wigan in the playoff semi-final in 2014, I remember feeling real excitement as I was holding the banner saying 'We're going to Wembley'. You realise not everybody gets the chance to do that."
Onuoha, who played for the North East outfit between 2010 and 2011, believes the magnitude of the occasion will hit home for the Black Cats when they arrive at Wembley and he hopes they will do enough to come out on top, as the "awful" feeling of defeat in the final is one they will seek to avoid.
"When you're getting ready for the game and you arrive [at Wembley], you understand the context of the game in terms of going into the next division. But then also, I've spoken with some of my friends like Joleon Lescott and he said, it's only ever a great day if you win. You understand the importance of it because to be at Wembley and lose is awful, I've heard it's literally awful because there's nothing worth celebrating.
"You've had all your fans out there. There's the hope of something being at the end of it because you don't play there for nothing, you're not going to play out a draw, there has to be a result on the day and it has significant meaning to it, which is why it's being played at Wembley.
"This is a one-off, this is the opportunity and you can't do anything that either plays into the opposition's hands or plays into not being at your absolute best for that occasion."
Onuoha also believes that they must put any nerves that they may have aside if they are to succeed this weekend, adding: "When you arrive, you stay at the hotel and you can see the stadium from the hotel. You see your teams advertised on the boards and stuff outside, you get in there you see the crowd it's incredible.
"It's truly, truly historic to play there and you think of all the people that have played there beforehand, but in the same breath, you don't want to be overawed by the occasion.
"I think whoever arrives there and feels a sense of 'Oh my god, I'm at Wembley, this is really nerve-wracking', you know you'll see them struggle. You can't be comfortable because you don't play there every single time, but you try and play your best game at Wembley because there's something on the line and if you manage to do that, then you get rewarded."
Alex Neil's Sunderland head into Saturday's final unbeaten in their last 15 league games and they have performed well against Wycombe this term, beating them 3-1 on home soil back in August before playing out an entertaining 3-3 draw at Adams Park in January.