TalkTalk chief executive Dido Harding is to step down from the role after seven years.
Her departure is part of a reshuffle at the telecoms company as the group's founder Sir Charles Dunstone moves up from chairman to executive chairman.
News of Ms Harding's departure was announced alongside a third quarter trading update which saw group revenue fall from £459 million to £435 million.
Ms Harding will be succeeded by managing director of consumer, Tristia Harrison when she leaves the role in May.
TalkTalk was hit by a cyber attack in 2015 where hackers accessed the personal details of nearly 160,000 people. The incident led to tens of thousands of customers deserting the firm.
The debacle was branded a "car crash" by the then information commissioner Christopher Graham.
Following today's announcement, Ms Harding said: "After seven extraordinary and fulfilling years, during which we have transformed TalkTalk's customer experience and laid the foundations for long-term growth, I've decided it's time for me to start handing over the reins at TalkTalk and focus more on my activities in public service."
Sir Charles's new role sees him stepping down as chairman of retailer Dixons Carphone.
Charles Bligh, managing director of TalkTalk Business, will become chief operating officer.