Border Force officers swooped on the London airport at the weekend and carried out two arrests, one of which was a 28-year-old woman from the Doncaster area.
The other woman, Tara Hanlon, 30, from Leeds was also arrested and has been accused of money laundering after she was stopped with almost £2 million in cash stashed into five suitcases.
Hanlon was set to catch a plane to Dubai when she was halted at Heathrow Airport Terminal 2 at around 8pm on Saturday.
Border Force officers searched five suitcases and found a whopping £1.9 million in sterling notes – the largest amount uncovered at the border in 2020 to date.
An investigation was launched by the National Crime Agency (NCA).
Chris Philp, Tory MP and minister for immigration compliance and the courts, said: "This is the largest individual cash seizure at the border so far in 2020 and I am delighted with the efforts of Border Force officers.
"Preventing the export of undeclared cash from the UK is a vital step in clamping down on organised criminal gangs."
Hanlon was charged with money laundering and appeared at Uxbridge Magistrates Court where she was remanded in custody until her next appearance.
The other woman was arrested under investigation.
Heathrow is one of the world’s biggest airports and the second busiest in the world by international passenger traffic, as well as the busiest airport in Europe by passenger traffic, and the seventh busiest airport in the world by total passenger traffic.