The Phelps twins will join Daniel Radcliffe, Rupert Grint and Emma Watson as well as American filmmaker Chris Columbus to discuss the films and explore their creation in depth.
The highly anticipated retrospective special, titled Return To Hogwarts, will be released on Sky and streaming service Now on January 1, 2022.
Fellow stars including Helena Bonham Carter, Robbie Coltrane, Ralph Fiennes, Jason Isaacs, Gary Oldman, Imelda Staunton and Tom Felton also feature along with Mark Williams, Bonnie Wright, Alfred Enoch, Ian Hart, Toby Jones, Matthew Lewis, Evanna Lynch.
Producer David Heyman and filmmakers Columbus, Alfonso Cuaron, Mike Newell and David Yates will also feature.
In a recent interview with the Express and Star, Oliver, who played George Weasley in the Harry Potter franchise, said: "It's amazing there's so much interest and people still want to hear stories of us talking about Harry Potter.
"There are children, aged eight or nine, who weren't even born when we finished, who love the films and so it's amazing to think there's a new generation to enjoy them.
"I met some fantastic people working on the films – as a cast, it's like people you go to school or university with.
"When you hook up, it always feels like exactly where you left off."
"I'd do it again and dye the hair for one more crack! It'd be good to do at some point and it would be well greeted I am sure."
And, having lost his twin, what would George be up to?
"I see him as a mad entrepreneur, the type of guy who would be on Wizard's Dragon's Den," Oliver laughs.
"Having a setback in the family, like Fred's death, things could have gone one of two ways for him but I'd like to think it'd have spurred him on.
"James and I have spoken about it and said that, maybe, George could still be running their shop, and Fred could be like the ghost, helping to stop people from stealing stuff. So there's always that possibility. There's a 20-part drama or a comedy series in that!"
Harry Potter 20th Anniversary: Return To Hogwarts will be released on Sky and streaming service Now in the UK and on HBO Max in America on January 1, 2022