Davina McCall's Channel 4 quiz show will have a celeb edition on Friday, February 3.
O'Leary and Cotton will be competing to win money for the CoppaFeel! charity, which aims to erase the late detection and misdiagnosis of breast cancer.
Previous celebrities on the hit show have included Larry and George Lamb and Jack Whitehall and his dad Michael.
Million Pound Drop is currently airing on Friday and Saturday nights on Channel 4.
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