Workers gave bosses nearly two billion hours of unpaid overtime last year, or the equivalent of a million full-time jobs, unions have said.
The public service trade union Unison told International Business Times UK: "These figures represent terrible reading for people across Britain. We are already one of the hardest-working nations in the world.
"It is bad for the family and very unhealthy for the individual.
Research showed the extra labour was worth £29.2 billion to the UK economy, with London and Southeast workers doing the most unpaid work.
The figures from Labour Force Survey Summer Quarter 2011 found 5.3 million workers put in an average of 7.2 hours of unpaid overtime a week last year, worth around £5,300 a year per person.
TUC general secretary Brendan Barber said: "The heroic amount of extra unpaid hours put in by millions of workers make a vital - but often unsung - contribution to the UK economy."
Workers in London (26.9 percent) and the Southeast (25 percent) were still the most likely to work unpaid overtime. Workers in the West Midlands (up 3 percent) and the Northeast (up 2.2 percent) experienced the sharpest rise in the likelihood of working unpaid overtime over the last year, the TUC analysis said.
It said reducing the amount of unpaid overtime would not translate precisely into extra jobs.
It admitted many of the extra hours were a result of a British work culture of pointless presenteeism but the organisation said persistent and excessive hours of unpaid overtime was holding back job creation.
Some employers were also forcing staff to work extremely long hours that could damage their health when taking on extra employees would be far more productive and provide much needed jobs, it said.
"While many politicians and financial institutions have spectacularly failed to do their bit to help the UK economy, millions of hard-working staff clearly have and we hope employers congratulate them for their efforts on Work Your Proper Hours Day this year," Barber said.
"But while many of the extra unpaid hours worked could easily be reduced by changing work practices and ending the UK's culture of pointless presenteeism, a small number of employers are exploiting staff by regularly forcing them to do excessive amounts of extra work for no extra pay.
"This attitude is not only bad for workers' health, it's bad for the economy too as it reduces productivity and holds back job creation.
"No-one wants to see us become a nation of clock-watchers. But a more sensible and grown-up attitude to working time could cut out needless unpaid hours and help more people into work."
In the run-up to Work Your Proper Hours Day on 24 February, the TUC will publish information and advice for staff and bosses on cutting down on unpaid working hours.