The 24-year-old fly-half cum full back has been undergoing counselling for alcohol issues and was left out of his country's initial 25-man party last month.
He hasn't played for his Super XV franchise the Melbourne Rebels since mid-May but Beale has done enough in training with the rest of the Wallaby squad to show Deans that he is more than capable of starring in the mouthwatering series, which begins in Brisbane a week on Saturday.
"We believe in his ability to cope and, for anyone who has seen Kurtley play, he's got the fastest reflexes and anticipation in the game," said Deans.
"He had to obviously cater for his physical needs and his mental needs and had to assure us and his team-mates he'd done that. From what we've witnessed at training, he's ready to go.
"The fact that we've got him here is indicative of the fact that we believe he can cope."
Beale admitted that he feared he may miss the once-in-a-lifetime series and he now intends to make the most of his unexpected chance to shine once more on the big stage.
The former Waratahs playmaker was widely regarded as the best full back in the world game in 2010 and 2011, before impressing at fly-half on the Qantas Wallabies' end-of-year tour of Europe seven months ago.
Now he isn't worried where he plays against Britain and Ireland's elite, just as long as he can help Deans and co secure a famous success in the coming weeks.
"I had to work on a few things off the field and I feel like I've done that now, with the support of close family and friends, with the ARU, the Melbourne Rebels and a lot of my close team-mates, they've supported me all the way along," said Beale.
"I'm very grateful for that. Without their support, it would have been tough at times.
"Full back, No10, even on the wing…I don't mind as long as I'm helping the boys. I really enjoyed playing No10 last year but I also enjoy playing full back…
I'm just going to take this opportunity with both hands and try and help the Wallabies get a good win over The Lions.
"It's a once-in-a-lifetime opportunity, a great honour, and to represent your country like this is a pinnacle.
"I'm very, very excited, over the moon. It's time to kick on and move on with my life."