Onions' last Test appearance came against West Indies over a year ago, but the 30-year-old has been included in England's 13-man squad for the fourth Investec Test against Australia, which starts at Emirates Durham ICG on Friday.
The fast bowler knows it will not be easy to break into an England side who have already retained the Ashes after winning the opening two Tests at Trent Bridge and Lord's before drawing at Old Trafford, but he insists he is ready to take his chance given the opportunity.
"I'm champing at the bit and I'm excited," he said in a press conference broadcast.
"I feel ready, I'm delighted to be here, delighted to be part of the squad. If you're in the squad then you're up for selection, you've got a chance of playing.
"I was disappointed not to be involved in the squad for the last game, but to be here at Durham, where I've played all of my cricket and to be from the north east, (I'm going) to be very proud to put that England shirt on.
"I feel as though I've played well for Durham this year and if the chance did come along I'll be ready."
Gateshead-born Onions, who has made nine Test appearances for England, added: "I still feel a bit nervous, but they are excited nerves really.
"The prospect of a playing a Test match cricket again, and playing in front of your home crowd, it's gonna be fantastic if I was given the opportunity to play."
Onions appreciates he faces a tough task to force his way into the side, especially with fellow fast bowler Chris Tremlett also included in the squad, but he hopes to get the opportunity.
On the prospect of England possibly rotating their bowling attack having already secured the Ashes, Onions said: "As a cricketer you want to play every game, being realistic you're probably not going to be able to if you play all three formats.
"For someone like myself where the red ball is my forte I want to try and force my way into the side.
"It's not easy, we've got a great crop of fast bowlers. Obviously with Tremlett and some of the young lads coming through as well, it's a privilege and an honour to be part of the squad."
England ensured they would retain the Ashes with their draw at Old Trafford, but Onions dismissed any suggestion the players would be taking their foot off the pedal as Alastair Cook's men seek to seal the five-match series.
"The rivalry between England and Australians will be huge. We want to win the two games, we want to perform as well as we can, we want to try and keep our standards high, try and win this series and this is a big game for us," he said.