But she has promised fans she will return in 2004 after a year away from Albert Square.
The 65-year-old actress said the decision to leave had been difficult but one that she had to make for the sake of herself, and that of her character Peggy Mitchell.
"This has been a very hard decision for me to make, because I'm so happy here on EastEnders, but it's been a long time without a proper break.
"I just feel some time off would be good for me, and probably the character too," she said.
"But I'm certainly looking forward to coming back. EastEnders is where my heart is, it's like my home, and this is where I see myself ending my career."
Windsor, who rose to fame thanks to her saucy characters in the Carry On films, plays one of EastEnders' most high-profile characters.
Wayward sons
As matriarch Peggy Mitchell, she has been at the centre of many explosive storylines, including a fight with breast cancer, being cheated on by husband Frank, and having to deal with wayward sons Phil and Grant.
Windsor was made an MBE in 1999 and is married to Scott Mitchell.
Her first husband was gangster Ronnie Knight, who was jailed for his part in a £6m robbery, and had links with the notorious Kray twins.
EastEnders' executive producer, Louise Berridge, praised Windsor's dedication to the soap, saying she never taken more than a fortnight off at a time in her eight years on the show.
"Of course we will all miss her enormously, but on a show as long-running as this one, it is obviously important for the artists to take occasional breaks," she said.
A big storyline is promised for Windsor's return to EastEnders.