Three-quarters of a million people will work on Christmas Day with no guarantee of extra pay and over 35,000 employees will work for nothing, according to the TUC.
Half the people working on Christmas Day are either in the nursing and social care sector or work in hotels and restaurants.
The TUC has called on the European Commission to give UK workers a legal right to holiday pay on Bank Holidays and a choice between being paid double time, or normal time plus a paid day's holiday in lieu if they have to work.
The UK is the only country in Europe where employees don’t have the right to holiday pay if they take bank holidays off and where companies are able to include bank holidays in the 20 days annual leave their staff are legally entitled to.
The TUC is also calling on the UK government to introduce three new bank holidays to bring the UK in line with the European average.
Brendan Barber, TUC general secretary, said: "It's about time the season's grafters got paid more for working over the Christmas holidays and it's about time Scrooge bosses had to give holiday pay to people who take time off work to enjoy the festivities."
"A bit of goodwill from the government and from Europe would make Christmas a lot merrier for millions of UK employees and their families."