The star’s barrister told Mr Justice Tugendhat of the admission by rap artist Justin Edwards during a hearing in London.
itn - Tulisa speaks: Response to leaked sex tape on MUZU.TV.
Jacob Dean said: “Mr Edwards has admitted responsibility for publication of the video, apologised for it, and promised not to do it again.”
A statement will be read out in court on Thursday by Ms Contostavlos’s solicitor Jonathan Coad, who will give details of the settlement of her claim against Mr Edwards.
Yesterday’s news followed an earlier hearing in the case during which the same judge heard that Mr Edwards denied posting the sex tape and regarded the distribution of the footage as “ungentlemanly”.
Ms Contostavlos, who shot to fame as a member of hip hop group N-Dubz and landed a high-profile role as a judge on the X Factor talent show, launched legal action against Mr Edwards and others following the emergence of the footage.
She won a High Court order in March banning publication of footage showing her “engaged in a sexual act”.
The singer and Mr Edwards had been in a relationship in their teens which ended in 2009.
In an internet statement broadcast on YouTube, the 23-year-old described being “devastated” and “heartbroken” over publication of the tape.
She said: “When you share an intimate moment with someone that you love, you care about and you trust, you never imagine for one minute that that footage may at any point be shared with the rest of the UK or the rest of the people around the world.”
Her case against a number of other defendants, over their alleged involvement in the distribution of the tape, will continue.