A study of more than 4,000 people aged 18 to 30 by the Young Women’s Trust found those in London were most likely to report being underpaid, while those in the East Midlands were least likely.
The issue disproportionately affects black people, the survey revealed, with 25 per cent reporting illegally low wages.
The charity said many young people were facing a financial “crisis” and falling into debt because of low pay.
Young Women’s Trust chief executive Dr Carole Easton said: “Paying young people less than the minimum wage is not just illegal, it is immoral.
“Low wages are leaving many unable to afford the basics. When the bus to work or an hour’s childcare cost more than an hour’s wages, it’s no wonder so many young workers are falling into debt and resorting to food banks.
“Young Women’s Trust is calling on the government to crack down on employers who are not complying with the law.”
She added: “Alongside enforcing existing laws, ministers should also raise the minimum wage for young people by extending the national living wage to under-25s, who can currently be paid less for the same work.”
A Department for Business spokesman said: “It is illegal for employers not to pay at least the national minimum wage.
“This year the government is spending a record £26.3m on ensuring the UK’s lowest paid workers get what they’re owed, and we’ve also put in place reforms ensuring employment law and practices keep pace with modern ways of working.”
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PA contributed to this report
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