The former N-Dubz star was facing a charge of being concerned with arranging a cocaine deal worth £820 last year.
She vehemently denied brokering the deal, which was exposed in the Sun on Sunday newspaper last June.
On Monday at Southwark Crown Court, the judge threw out the case because there were "strong grounds to believe" that undercover reporter Mazher Mahmood - dubbed the 'Fake Sheikh' - had "lied" at a hearing before the trial started.
Taking to her Twitter page on Monday evening, Tulisa expressed her gratitude to her fans, writing: "Thank you to everyone for your amazing messages of support today."
Earlier that day she had called for the police to investigate Mr Mahmood and "put an end to his deceits". He has since been suspended by The Sun newspaper pending an investigation.
Tulisa also expressed her wish to get back to work, commenting: "I am now looking forward to resuming my career.
"I will use these experiences to make me stronger."