Lindsay Sandiford, 55, was caught with 4.8kg of the drug stuffed in the lining of a suitcase as she arrived in Bali, according to customs officials.
After her arrest on the Indonesian island last week she agreed to take part in a sting operation in which police swooped on four other suspects.
Another British woman, two British men, and an Indian man were arrested over the huge seizure.
The head of Bali’s drugs squad said the two British men, identified by the initials BP and JAP, were believed to be senior figures in a major drug-smuggling syndicate.
The news agency Australian Associated Press reported that Mulyadi, who goes by one name, said: “It’s an international network controlled from abroad.”
Ms Sandiford, originally from Teesside, England, is thought to have told police that she only agreed to make the smuggling trip because her children in the UK were being threatened.
She was paraded at a press conference alongside the drugs, wearing an orange prison T-shirt and hiding her face from cameras.
Masked armed officers in Kuta, a town on the holiday island, flanked her as she was brought into the room and a customs official cut open packages wrapped in brown tape to reveal a white powder.
Ms Sandiford, listed on immigration documentation as a housewife, was stopped as she arrived at Bali’s Ngurah Rai International Airport on a Thai Airways flight from Bangkok, Thailand on May 19, customs official Made Wijaya said.
Two days after her arrest she was contacted by the second British woman, identified by the initials RLD, at which point a meeting was arranged.
Mr Wijaya said at the press conference: “After weighing, the total cocaine is 4.791kg.”
The drugs have an estimated street value of 23.9 billion Indonesian rupiah (€2m), he said.
Indonesia has extremely strict drug laws, and the official said Ms Sandiford was likely to face charges that carry a death penalty.
He said: “This is a big international network. The charge against them would carry the death penalty,”
Another 68g of cocaine, 280g of powdered ecstasy, and a small amount of hashish were also seized following the arrest of the other gang members at separate locations in Bali, officials said.