A source told the Mirror: "We are in talks with the Prince's representatives and understand he is eager to support the event, as he has done previously. We're hopeful Kate will be able to do it too."
We cannot wait to see how Kate rocks the workout look.
It's not just royalty that's getting involved, as 100 MPs, possibly including David Cameron, plan to run through St James's Park for the Westminster Mile on March 14.
Plenty of celebrities have signed up for fundraising challenges too. David Walliams swam 140 miles of the River Thames and raised more than £1million last year. Blue Peter presenter Helen Skelton is on a 500-mile Antarctic trek. In addition to the Great Sport Relief Bake Off, there will be another Let's Dance for Sport Relief on TV.
JLS have recorded an official Sport Relief single. We're interviewing the lads today, so stay tuned!
A night of live TV on BBC1 is planned for March 23.