Acts in talks to join Williams, 36, include Gary Barlow, Pixie Lott and JLS plus Kasabian, Stereophonics and more to be announced over the coming weeks.
“This is something special for Help for Heroes,” the Sun quoted a source as saying.
“All the bands and acts involved feel incredibly strongly about raising money for the families of our Armed Forces who are left without their loved ones.
“The bands in particular have been keen to get involved and offer their support for such a great cause because they are the ones the soldiers listen to.
“As is always the case with these gigs, getting everyone in the same stadium on the same day is a logistical nightmare.
“It will be incredibly emotional.