A CIPD survey found 59% of employees who graduated in the last two years are not currently working in a field or profession related to the degree they studied.
The survey, Focus on graduate jobs, which is based on responses from more than 700 graduates in employment, comes against the backdrop of Government pledges to significantly increase - to 75% - the proportion of young people they want to secure a degree or equivalent level qualification.
In addition, the survey, conducted for the CIPD by YouGov, found among graduates not working in a field related to the degree they studied 58% said this was because they were unable to find a suitable job and 28% said their degree did not equip them with the skills that they need for the workplace.
The survey also found 21% of recent graduates chose a new career path after finishing their degree and a quarter of recent graduates (24%) had since decided to postpone the start of the careers entirely.
The figures raise questions over the Government's continued efforts to expand enrolment on university degrees, and their desire to chase the new 75% target for young people to be educated up to degree level, particularly at a time when the UK labour market has contracted significantly.
Tom Richmond, skills adviser at the CIPD, said: "The rising number of students unable to work in jobs related to the subjects they studied at university threatens to create a ‘disillusioned generation' of graduates, unable to find graduate-level employment but still saddled with thousands of pounds worth of debt.
"To compound this, the recent announcement of an extra 20,000 university places in this year's Budget makes the creation of a ‘disillusioned generation' even more likely.
"Government should focus on understanding the needs of learners and employers, as well as providing young people with better information about the realistic employment prospects and salaries typically available for holders of degrees in different subjects. This will help ensure there is a better link between demand for, and supply of, graduate jobs.
"The Government also needs to spend more time and effort developing and promoting the new vocationally-based diplomas for 14 to 19-year-olds to ensure that more young people have the key skills to enter the workforce at age 16 or 18, rather than encouraging such a high proportion of them to study for degrees. Our survey suggests this over promotion of university or equivalent level study could leave many without the knowledge and skills that will genuinely help them find graduate-level work and apply it in the workplace."