Sabina Rova, 23, secured work as a cleaner at the five-star Hilton Hotel in Park Lane, The Other House apartments in South Kensington and at the Club Quarters Hotel in Trafalgar Square to carry out the burglaries.
Westminster magistrates court heard Rova — who is suspected of being part of an organised crime group — took Cartier watches and rings, Rolexes, and Dior pearl earrings, and used stolen credit cards for shopping sprees.
After raiding the rooms of the guests, she would walk out on her job and move on to the next target, the court was told.
Rova broke down in tears in December when she admitted the burglary at the Hilton, stealing valuables worth £187,000, as well as fraudulent use of a stolen bank card.
She was in tears again in court as she pleaded guilty to two more burglaries, including one where jewellery and watches worth £179,000 were taken, and another fraud.
Rova has been remanded in custody to face a sentencing hearing on April 5 at Southwark crown court.
Rachel Darlington, prosecuting, said: “In each case, Ms Rova gained work as a housekeeper, and used her position to access guests’ rooms in different hotels and stole valuable items. Following each burglary, she immediately left the hotel in the middle of her shift, never to return.”
The court heard a custom-made diamond jewellery item worth 80,000 euros, a 25,900 euro pair of Cartier earrings, and a Rolex Oyster watch valued at 19,500 euros were among the items stolen from The Other House on September 15 last year.
In the Hilton raid on July 7 last year, Rova, who is originally from Romania, used a stolen bank card to buy goods at the nearby Footlocker store on Oxford Street.
At an earlier hearing prosecutor Alex Matthews said Rova, who was living in Walthamstow, is part of an “organised crime group”.
At a hearing last week, she pleaded guilty to two counts of burglary and fraud by false representation.
Magistrates adjourned so she could be sentenced at crown court, with all the offences being dealt with together. She was remanded back into custody until the hearing next month.
In a statement from The Other House in South Kensington said it “has 24/7 security and the safety and wellbeing of our guests is of utmost importance.
“The residents’ club takes any acts of wrongdoing seriously and has followed all processes and engaged with the authorities concerning this case.
“We can confirm that Sabina Rova is no longer an employee at The Other House.”