The actress, who plays mum-of-three Tanya in the BBC One soap, will take a break from the show next year but will return.
"I love playing Tanya and can't wait to find out what's coming up. All I know is there's a big secret that's going to come out at Christmas and it will affect the entire Branning family. It's huge and the fans will be shocked," Joyner told the Daily Star Sunday.
She added of her break: "I only took six months when I first had the kids and was very envious of everyone taking a year. But this way I'm still getting my six months - just before they start nursery - which is really nice.
"We're hoping to move back to the countryside as I'm a real country girl at and I want to spend as much time with the kids as I can. It's a little while off yet and I have no idea how they're going to write me out but I will be back."
Joyner previously teased that the Branning family will take centre stage during this year's Christmas episodes.