Theresa May is pledging to stop high street restaurant chains deducting money from tips given by customers to waiters and bar staff.
The move, which will require legislation, will stop some of the biggest names on the high street deducting up to 10% from employees' tips.
According to the government, while some businesses have changed their practices, Belgo, Bella Italia, Cafe Rouge, Giraffe, Prezzo and Strada all deduct 10%, and Ask and Zizzi 8%.
Announcing the move, the prime minister said: "The unemployment rate under this government is now the lowest since the 1970s - but we want to ensure that everyone is treated fairly in the workplace.
"That's why we will introduce tough new legislation to ensure that workers get to keep all of their tips - banning employers from making any deductions. It's another way we are building an economy that works for everyone."
The promise comes in the government's response to a consultation and will benefit many of the 1.8 million people who work in the hospitality industry in the UK.
The government says the change will be fairer for both workers, who get to keep the tips left for them by customers, and customers, who leave tips specifically for the service they receive.
The consultation showed that restaurant customers are overwhelmingly in favour of the tips they pay going to the people that serve them.
The government also says it is another example of how it is cracking down on exploitative practices in the workplace.
Sky News is calling for an Independent Leaders' Debate Commission to oversee and organise election debates
"We want to ensure both that workers' rights are always upheld, and that they're rewarded for their hard work, as part of our modern industrial strategy to create better paid and higher quality jobs across the country," said a government source.
"The change is part of the government's drive to back businesses to create good jobs while making sure the system works for ordinary people.
"It is in addition to the introduction of the National Living Wage, which when it was introduced increased the wages for roughly a quarter of the workers in the hospitality industry."
Responding to the PM's announcement, Rebecca Long Bailey MP, Labour's shadow business secretary, said: "This is now the fourth policy the Tories have copied from us at their conference, as they desperately try to catch up with Labour.
"It's beginning to feel like Groundhog Day. It's a shame that Unite have had to fight so hard to extract this concession from the Tories.
"And if only this pledge went as far as Labour's promises to precarious and freelance workers.
"Under Labour, gig economy workers and the self-employed will get sick pay and parental leave, just like everyone else."