More than 14,000 people in Northern Ireland have been out of work for at least a year, according to new research.
This marked the biggest increase in the UK, the TUC said. Northern Ireland's peak for unemployment is not expected to arrive until some time after Great Britain with the region slower to emerge from recession.
TUC general secretary Brendan Barber said: "Across the country thousands and thousands of people have been struggling to find work - some of them for several years now - and for their families there won't be much to celebrate this Christmas."
The biggest increase in long-term joblessness was in Northern Ireland where 14,325 people have been on the dole for at least a year, up from 9,860 over the past year, while parts of London have also been badly affected, said the TUC.
Mr Barber added: "While many families with working adults may be tightening their belts a little this Christmas, the thousands of long-term unemployed households will be anxiously juggling their family budgets, knowing only too well that their JSA of £65.45 isn't going to buy much Christmas cheer this year.
"With many local councils in the process of issuing redundancy notices to thousands of their employees over the coming weeks, the future for those about to lose their jobs and those who've been out of work for some time looks especially bleak. The Government's huge cuts to public spending will see thousands of public sector workers being made redundant in the new year, and those working in the private sector could be hit just as hard."
Almost 250,000 people across the UK have been out of work for more than a year, with many spending their third Christmas on the dole, according to the research.
The TUC said the number of long-term unemployed claiming Jobseeker's Allowance (JSA) has more than doubled since the recession started at the end of 2007, from 117,000 to 243,000. Total long-term unemployment, including those not eligible for benefits, increased to 839,000 in October, a 34% rise on the year and the highest level since February 1997.
A Department for Work and Pensions spokesman said: "The coalition Government is focused on restoring the economy and supporting private sector jobs growth. There are jobs available in the economy, with Jobcentre Plus alone taking on over 70,000 new vacancies every week - that's around one million coming up through Jobcentre Plus every three months.
"Today we are inviting organisations from the private and voluntary sectors to deliver our new Work Programme which will transform the welfare landscape in Britain. We will provide much better back-to-work support for hundreds of thousands of people so that they can take up the offer of employment and stay there."