The pair were finalists on talent show Popstars and launched careers in pop bands Hear'say and Liberty X respectively. Marsh currently plays Michelle Connor in Coronation Street, while Heaton has recently appeared in a number of reality shows including Celebrity Big Brother.
Marsh told the Belfast Telegraph: "It's going to be a great night and it's for a fantastic cause. I'm so excited about seeing Riverdance, as I've never seen it live before, so that will be a real treat too."
Heaton added that she too is looking forward to the ball, which takes place on October 3, saying: "I can't wait to go back to Belfast. It is such a great city and I am so excited to be returning for the White Sapphire Ball.
"The Children's Hospice is a wonderful charity and as they do such amazing work I am delighted to be able to attend the event to support them."
Emma Rigby, who plays Hannah Ashworth on Hollyoaks, is also among guests at the ball.
> 'Oaks McCarthy supports charity ball