The actress will reprise her role as Sharon Rickman (previously Watts) on August 13, after previously playing the character from 1985 to 1995 and 2001 to 2006.
Dean explained that she was pleased to be returning to Albert Square and reuniting with Steve McFadden (Phil Mitchell).
"It's been wonderful coming back. I was really nervous, it was like the first day at school - but my first scenes were on location, so I was eased back into it," she told the Daily Star.
"It's been great working with people like Scott Maslen and Jo Joyner, as well as the lovely Steve McFadden.
"It's been a bit of a whirlwind really. I did 11 years straight the first time I was in EastEnders and then came back for another five years.
"This was the first time they'd asked me to come back since I left and it was a bit of a no-brainer really."
She added: "It was nerve-racking as I'd been away for six years but they came up with this lovely storyline for me.
"When I walked back on set for the first time, I know it sounds like such a cliché but it really was like coming home."
Dean recently said that it felt as if she had never been away from the soap.
Watch a trailer for Sharon's return below: