The 54-year-old cook was prevented from boarding a flight from London Heathrow to Los Angeles on Sunday morning.
The UK’s Daily Mail newspaper reports Nigella arrived alone at the airport on Sunday morning to catch a British Airways flight to LA.
She is believed to have checked in and passed security before being told she couldn’t board the plane.
US authorities are thought to have refused her entry to the country on the grounds that she admitted to using cocaine in a dramatic courtroom confession last year.
Nigella is now expected to hire lawyers to fight the ban, but that could take weeks, putting her career on US show The Taste in jeopardy.
