Vicki Fowler is returning to EastEnders in January.
The character was last seen in Walford in 1995 aged nine before she left for the USA with mother Michelle for a new life.
She will be played by newcomer Scarlett Johnson.
Vicki is step-sister to Sharon and niece of Mark and Martin Fowler, as a result of a late-night liaison between Michelle Fowler and Den Watts in the Queen Vic.
Scarlett says: "When I got the call from EastEnders I was in complete shock - I'd been to two auditions but hadn't heard anything for so long that I just put it out of my mind. So the news, when it came was really out of the blue.
"Everyone on the cast has been really welcoming - Kim Medcalf is my mentor which is great and James Alexandrou, my on screen uncle Martin, has been so supportive.
"It's surreal joining a show that is such a British institution and I am such a big fan of, and strange to have scenes with people like Letitia Dean and Wendy Richard who I've looked up to."