Elaine Douglas and Tommy Brooks, who are Jamaican nationals, were put up in hotels for almost a year before staff at the Royal Borough of Kensington and Chelsea (RBKC) realised the flat they claimed to live in did not exist.
The pair, both 51, also tried to take advantage of a scheme allowing residents of the tower leave to remain in the country for at least five years in case fears over immigration status prevented victims coming forward.
Douglas was housed in the Radisson Blu in Kensington for 276 nights at a cost of just over £55,000 to the council, as well running up a room service bill of £267.35.
After complaining about the food in the hotel, she was given a pre-paid credit card, running up charges of more than £11,000.
She was also handed a pre-paid Oyster card so she could travel free of charge.
Brooks also started off at the Radisson Blu before being moved to another hotel.
He spent 243 nights in hotel accommodation, costing RBKC more than £49,000.
He racked up a room service bill of £276 and charges of £9,000 on a pre-paid credit card, and was also given an Oyster card.
In total, he claimed £58,396.89 in relief intended to help the victims of the fire, while Douglas claimed £67,123.35.
Both defendants today pleaded guilty to two counts of fraud by false representation and one count of obtaining leave to remain in the UK by deception at Isleworth Crown Court.
The offences took place between August last year until their arrest on 2 May this year.
Prosecutor Benjamin Holt said: “The defendants both claimed to have been together in the fire.
“Both said they were residing in flat 91 on the 19th floor – flat 91 is actually on the 12th floor.”
Mr Holt told the court both had managed to avoid immigration authorities for 16 years after entering the UK illegally in the early 2000s.
“Following the fire at Grenfell Tower the Government introduced a policy to allow those with insecure immigration status that had lost their homes to regulate their situation,” he said. “They were granted leave to remain for 12 months and that was later extended to five years.
“On 22 February 2002, Ms Douglas was refused leave to enter the UK and a flight back to Jamaica was booked for 24 February.
“She was deemed too ill to travel and a flight was rebooked for 8 March of the same year.
“She did not attend for that flight and nothing has been heard of her in the intervening 16 years.
“Mr Brooks arrived on 11 August 2001 and was granted leave to remain until 9 September of that year.
“He applied for leave to remain and that was granted until February 2002, and in the intervening years nothing was heard of him.”
Judge Robin Johnson adjourned sentencing until 13 June - almost a year since the disaster - to allow time for Brooks to be legally represented.
Seventy-one people died in the fire on 14 June last year, including an unborn baby.
Members of the victims’ families were seated in the public gallery to watch Brooks and Douglas’s case.
The defendants were remanded in custody until sentence.