Metro reports that the singer has told writer Sean Smith about a secret arrest in 2008 for an authorised biography.
For the first time, Contostavlos has admitted to an incident in September 2008, when a fight involving 20 people broke out at the birthday party of her then-boyfriend Adam Bailey.
During the chaos, a man was stabbed and wounded. Fearing for her career, the N-Dubz star says she called her manager Jonathan Shalit before phoning police.
Contostavlos was later arrested and forced to take the stand at a court trial, after Bailey was accused of wounding with intent and dangerous driving.
The incident occured just a month before N-Dubz released their hit debut album Uncle B.
"Tulisa had the presence of mind to call Jonathan Shalit and any fall-out was well-managed," Smith writes in the biography, currently serialised in The People. "Incredibly, the arrests of Tulisa and Bailey never made the papers at the time. That would certainly not happen today, when she is a far bigger star."
Since rising to fame in N-Dubz, Tulisa has launched a solo career and is currently taking part in her second series as a judge on The X Factor.