The 25-year-old is said to be the only high-profile exit from the ITV2 reality series, according to The Sun.
Filming on the latest series began yesterday, ahead of its return on Sunday (February 24).
Kilbey was banned from driving for two years and was also handed a community service order earlier this month after admitting a drink-driving offence.
However, insiders have stated that her decision to leave was not in relation to her drink-driving case, and she had been thinking about quitting for a while.
A source said: "It was a mutual decision between her and producers. She feels it is the right time to move on."
She was arrested in Camden on January 12, after police noticed her driving "erratically".
Her brother Tom Kilbey previously announced last year that he is taking a break away from the show.
TOWIE Season 7 - Cast pictures: