Mrs Brooks, 45, and her racehorse trainer husband Charlie, 50 – accused with her of conspiracy to pervert the course of justice – stood side by side at Southwark Crown Court in south London.
Several other people including former News of the World journalists and security staff also denied charges.
There was standing room only for the hearing, with those watching including Labour MP Tom Watson.
Dressed in black and with her red hair pinned up, Mrs Brooks, also a former editor of both the News of the World and The Sun, entered not guilty pleas to five charges.
Brooks, of Churchill, Oxfordshire, denied conspiracy to hack phones between October 3, 2000, and August 9, 2006.
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