More than a quarter of 20 to 30-year-olds live with their parents, a massive increase since the start of the economic downturn, according to the Office for National Statistics.
About 3.3 million of adults aged 20-34 lived with their parents in 2013, an increase of 669,000 since 1996.
Nearly twice as many young men live with their parents compared to women - 2.1 million against 1.2 million - who are more likely to form relationships with older partners, move away to university or become a lone parent when a relationship breaks down, said the ONS.
The rise in young adults living with their parents in 2013 occurred despite the number of 20 to 34-year-olds staying roughly the same over the last seven years.
Attempts to get more than a million young people into work are being hampered by excessive bureaucracy and central government control, council leaders have claimed.
The Local Government Association (LGA) said a new, more local approach to tackling youth unemployment could cut the number of young jobless people by a fifth.
A report complained of an "overly complicated" system of tackling youth unemployment, with 33 different national schemes, covering 13 different age boundaries, costing £15 billion a year.
More than 94,000 people completed hair and beauty courses last year, even though there were only 18,000 new jobs in the sector, while in construction, around 123,000 people were trained for around 275,000 advertised jobs - more than two jobs for every qualified person, said the LGA.