The creation of the role will see Keers keep her board-level status, but she will now be responsible for all customer-related matters across the company and will report directly to chief executive David McGlade.
Keers said she would ensure "that the customer is represented at every level in O2", adding she will develop further customer-focused initiatives to build on the success of ventures such as O2 Home and O2 Bolt Ons.
O2 is now seeking a marketing director to replace Keers, who will also have board-level status.
Keers will continue to have responsibility for all marketing until a replacement is found. She is in the process of establishing a team to work for her in her new role.
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