The number of people who are under-employed in Scotland has increased by 27 per cent (59,050) to 279,495 in the four years since early 2010.
Over the same period, unemployment fell by seven per cent from 205,000 to 190,000.
The TUC analysis of the Labour Force Survey reveals that of all the regions in the UK, only Northern Ireland has seen a higher rise in underemployment.
It shows that across the UK the number of people who count as under-employed - people working part-time because they cannot get a full-time job, or wanting more hours in their current job - has increased for both employees and the self-employed.
The Department for Work and Pensions (DWP) described the figures as "misleading" but TUC general secretary Frances O'Grady said almost 280,000 people would like to be working more hours than they are currently.
"With more jobs being created, you'd expect that under-employment would be on the wane too. But sadly with part- time, temporary and low-paid jobs often the only work that people can get, under-employment remains stubbornly high, and is still rising," he said.
"As the squeeze on pay continues, many people don't have enough money for everyday essentials, let alone the cash to cover any unexpected emergencies. With no let-up in their financial woes in sight, people are understandably looking to take on more hours just to keep the wolf from the door.
"In the last two years the number of people who say they would like more hours in Scotland has gone up by almost 60,000. Without a decent pay rise and the creation of more permanent, secure jobs, under-employment is unlikely to fall any time soon."
The analysis shows that while unemployment has fallen by more than 400,000 across the UK since early 2012, under-employment has risen by 93,000. And at 3.4 million, the current level of under-employment is more than a million higher (46 per cent) than it was before the recession. The fastest rise in under-employment over the past two years has been among self-employed workers.
Peter Kelly, director of the Poverty Alliance, said the figures showed it seemed to have become standard practice to cut hours or provide part-time work when the economy was supposedly in recovery.
"The past few years have seen a significant increase in the number of people in in-work poverty. More than half of children in poverty in Scotland live in a household where someone works. A big part of the solution to underemployment is ensuring that workers are paid a living wage," he said.
John Dickie, head of the Child Poverty Action Group in Scotland, added: "Despite UK Government claims, work is too often not the route out of poverty it should be, and slashing working tax credit and in work family benefits only serves to punish families who are doing everything they can to provide for their families. "
A DWP spokesman said: "The TUC's figures are misleading. Independent statistics show that there are over 100,000 fewer people who say they are under-employed compared to a year ago, and that full-time jobs account for more than three-quarters of the rise in employment since 2010.
"The proportion of part-time workers wanting a full-time job has just seen the biggest annual fall in over two decades. The overwhelming majority of those working part-time do so because it suits their circumstances."