Tulisa Contostavlos said her life had been "ruined" for the last year by what she called "entrapment" from an undercover reporter working for the Sun.
Speaking outside Southwark Crown Court, the singer and former X Factor judge called on the police and the Sun's publishers, News UK, to look into Mazher Mahmood's conduct.
The judge in the case said there were "strong grounds" to believe Mahmood had "lied" and given "entirely inconsistent" evidence.
More top news
Sunshine with blustery showers and longer downpours
Downton Abbey actress Joanne Froggatt is to star in a new ITV drama exploring the devastating cost of deceit.