Lytton’s character fled Walford in 2006, a year after arriving on Albert Square with a trouble past and a story to tell.
Daughter of soap villain Johnny Allen, Ruby soon found herself caught in the middle of a bitter feud between Johnny and resident hardman Phil Mitchell.
During her time on the Square, Ruby became close pals with Stacey Slater – played by Lacey Turner – but it was her closeness to her best friend’s brother Sean that caused her to leave Walford.
Now, after 12 years away, Ruby will return to the long-running soap hoping to reconnect with Stacey and carve out some sort of future.
On her return, Lytton said: “EastEnders was my first acting job out of drama school and opened so many doors for me. It’s wonderful to be given the opportunity to come back and explore my character and I’m excited to see what’s in store for Ruby.
“We last saw her twelve years ago as a young girl and now she is returning as a woman with scope for major change and some brilliantly challenging storylines.”
Boss John Yorke promised that viewers will see a “much more mature and confident Ruby” adding that she will be involved in “one of our biggest storylines later this year”.
Lytton came fourth in the 2006 series of Strictly Come Dancing, at the time becoming the youngest contestant to take part in the show at just 17.
The actress also starred as PC Beth Green in The Bill from 2007 to 2009 and toured the country with a theatre production of Grease.
EastEnders continues Thursday at 7.30pm on BBC One.