The 25-year-old denied being involved in the supply of class A drugs as she appeared at Westminster Magistrates Court.
Musician Michael Coombs, 35, who also uses the name Mike GLC, pleaded not guilty to the same charge.
Former X Factor judge Tulisa cut a sombre figure as she arrived to enter her plea, dressed all in black.
Immediately after her court appearance, she stopped in the foyer to greet and hug fans before composing herself to face the cameras outside.
Her lawyer then read out a short statement on her behalf.
Tulisa and Mike GLC were arrested in June after an undercover investigation by the Sun on Sunday. The singer is accused of being "concerned with the supply of 13.9 grams of cocaine" to the newspaper’s undercover reporter Mazher Mahmood, known as the 'fake sheikh', between May 20 and May 24.
Tulisa was forced to disclose her address to the court after her solicitor applied for it to be withheld to prevent "unwanted visitors".
Chief magistrate Howard Riddle ruled that "the address must be given" after considering the application, and Tulisa then told the court, "Just to let you know, after it being read out, in the next month or so I might have to move to a new address."
The judge granted both defendants unconditional bail and told them the case was to be sent to Southwark Crown Court, where they will appear on 9 January.