Some workers have likened their conditions to "slavery."
One hotel worker has published an anonymous blog, "Maid in London," which details some of her experiences.
"I work in the housekeeping department of a luxury four star hotel in London made up of 350 bedrooms for the rich, the even richer, and people who managed to get cheap Internet deals," the report says.
"My agency contract guarantees me a wage of US$32 per week….that's four hours work at the minimum wage of US$8.50 an hour."
"I'm expected to clean 16 rooms in a 7.5 hour day with a 30 minute unpaid lunch break that goes in the blink of an eye."
A chef says: "I am so tired of 16 to 18 hour days, seven days a week and zero appreciation from my employer."
Unite want all hotel owners to look at the report which according to Peter Kavanagh, Unite London regional secretary, "makes for grim reading."
"The London hotel sector is failing its workforce. It has become a byword for low pay and exploitation. If these stories tell us anything, it is that shameful work practices, similar to those exposed at Sports Direct, have no place in 21st century Britain."
According to Kavanagh, not a single hotel in the capital pays the London Living Wage of US$ 12.50 an hour and that workers in Manilla and Buenos Aires "are shown more respect when it comes to their basic human and trade union rights," despite London being the world's fifth largest economies.
The union remains concerned that despite many signatories to various ethical social responsibility agreements, big name hotel chains, including Hilton, Marriott and Intercontinental Hotel Group, are only paying lip service to workers' basic human and trade union rights."
Unite is calling on all London hotels to adopt a set of principles after the report revealed that 90 percent of all housekeeping staff say there are in constant pain caused by their job; 53 percent say they frequently miss meals and break because of their workload and staff shortages and over three quarters of chefs surveyed say they've had a "near miss" or accident at work due to overtiredness.
It costs an average of 160 a night to stay in a four star hotel in London.
Unite hotel workers are gathering in London on the South Bank near the London Eye to stage a protest to highlight their #UnethicalLondon complaints.