The 'Broken Heels' singer won X Factor six years ago under Cheryl's tutoring, and has since gone on to enjoy a successful career in music and on the stage.
Speaking with ITV's Lorraine today, Alexandra said Cheryl's return to the show would regenerate interest, adding: "I think the fact Mel B is there as well will give it an extra oomph and of course the fact that Louis hasn't gone anywhere, that makes me very happy!
"It's also great that Simon is back. I think it's nice for us viewers to see familiar faces."
There had been rumours earlier this year of Alexandra herself joining the judging panel, but she's currently occupied with her role in The Bodyguard in the West End.
She did, however, have an experience of life on the other side of the table before, when she filled in for Kelly Rowland as an X Factor guest judge during a previous year's auditions.
"I filled in for Kelly for one show and it was a lot of fun but I tell you something, being on the other side is as scary as being on the stage because I remember when I was doing the show and it was so nerve wracking!"
This year's X Factor will see the return of Simon Cowell and Cheryl Cole as judges for the first time since 2011, when they left to join the US version of the show.
Scary Spice Mel B is a new addition to the panel, while Louis Walsh is back for an ELEVENTH year in a row!
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Cheryl's X Factor highlights in pictures:
Copyright: REX/Ken McKay