"This is a world first for us!" the group said in a statement (via The Sun). "Reuniting with our old friend online for a one-off performance! 
"It's always great getting back together with Robbie and we are really excited to be part of this unique show that everyone can enjoy from home.
"We are also delighted to be supporting Nordoff Robbins and Crew Nation around this show, two charities very close to our hearts."
Robbie added: "I am really looking forward to performing with the boys again – it's always a pleasure. Nordoff Robbins and Crew Nation are both such brilliant charities and I'm thrilled to be supporting them around this show.
Take That (with Robbie Williams, middle back) on 01.11.1992 in Dortmund. (Photo by Fryderyk Gabowicz/picture alliance via Getty Images)© Getty Take That (with Robbie Williams, middle back) on 01.11.1992 in Dortmund. (Photo by Fryderyk Gabowicz/picture alliance via Getty Images)"If we can't go to the stadium…we'll bring the stadium to us." 
After years of feuding, Robbie joined the group in 2010 for the excellent Progress album and tour, and a handful of performances since – most recently on The X Factor in 2018, when Robbie was one of the judges with wife Ayda Field.
Jason Orange won't be taking part in the performance (at least he hasn't been announced to be) after he left in 2014, citing that he no longer wanted to commit to the lifestyle of making and promoting music.
Robbie recently admitted that no-one has any idea where Jason is, although he might have been joking in his typical Robbie style.