Research by the TUC suggested that 42,000 more people will not have a day off on 25 December compared with three years ago.
Nurses, doctors, chefs, bar staff, security guards, police officers and clergy are among those who will be on duty as normal.
The TUC said the biggest proportion of employees set to work on Christmas Day are in the North East (one in 28), East Midlands (one in 30) and South West (one in 31).
TUC general secretary, Frances O'Grady, said: "Christmas Day is a special day that millions of us spend with our nearest and dearest.
"So we should all spare a thought for the people who will be hard at work while we're opening our presents, tucking into the turkey and relaxing with our families.
"Many on duty on Christmas Day will be on low pay, especially in sectors like hospitality and social care."