The number of people classed as under-employed, including part-timers wanting a full-time job, has increased by a million since the start of the economic downturn in 2008, new figures have shown.
A total of 3.05 million workers were under-employed, with almost two-thirds in part-time jobs, said the Office for National Statistics.
The number of under-employed workers was fairly stable in the run-up to the recession in 2008 but has since leapt by almost half, the figures showed.
Occupations with the highest number of under-employed workers included cleaners, caterers and labourers.
The highest under-employment rates were in the East Midlands, Yorkshire and Humber, the North East and the South West, where more than 10% of workers wanted to work more hours.
The biggest increase in under-employment in recent years has been in Yorkshire and the Humber.
Regions with high under-employment rates had above-average numbers of part-time and young workers, as well as more low-skilled employees.
The average under-employed worker earned £7.49 an hour, more than £3 less than someone who was not under-employed, said the ONS.
More than one in five of workers aged 16-24 were under-employed this year, compared with 10% of those aged 35-49.