The pair revealed their exits on Twitter, with both of them hinting that they have different projects lined up for the future.
Fowler thanked her fans for their support, and revealed that she had agreed to leave the show following a meeting with producers.
"I Would like to be the first to announce... After a rollercoaster year and after meeting with producers today we have decided that my time on TOWIE has come to an end (sic)," she wrote.
"I am happy to be leaving the show on a high after 3 series and feel I am embarking on a new chapter in my life with exciting projects both personal and professional. Thank you for all your support during my time on the show and I hope to continue to keep you all entertained throughout 2012!!"
Meanwhile, Derbidge wrote: "Hiya! I really did not want you to all find out so soon but its out there, I am not in TOWIE anymore as I am moving onto different things."
Derbidge was rumoured to be facing the axe in December along with other stars in order to make way for new cast members.
Fowler's involvement in the show had been cast into doubt following allegations that she worked as an escort.
Former star Kirk Norcross recently revealed that he left the show because he became "fed up" with it, while Amy Childs explained that quitting was the "best decision" of her life.
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