The figures, released for the first time, are a mid-range estimate and the actual cost could be much higher.
They consist of £ 21 billion costs for businesses, £ 3.1bn to £ 2.2 billion of government and citizens.
Security Minister Baroness Neville-Jones said the government was committed to working with industry to address cybercrime.
For the moment, cybercriminals are "without fear, but they do not think they will be caught," he told a conference in central London.
"Frightening"
But efforts to get a grip on the problem has been hampered by the companies who did not want to admit they had been attacked for fear of "damage to reputation."
This also meant it was difficult to accurately estimate the cost to the economy - and the "worst case" would probably be much more than £ 27bn.
"It's a bit like terrorism - the more you know the more frightening than it seems," said the Baroness Neville-Jones.
But she said the government was not in "panic stations", adding that there was a strategy to address the problem and had committed £ 650 million over the next four years to do so.
The prime minister, David Cameron, Foreign Secretary, William Hague had met the heads of some of the largest companies in Britain, including Barclays, HSBC, Tesco and BA on Monday to urge them to take the problem seriously.
Baroness Neville-Jones said the ministers will unveil a plan to stop cyber-criminals and ensure more of them were prosecuted in the spring "and had agreed to form a joint working group with industry to address the problem.
Martin Sutherland, chief executive of Detrica, the consultant who compiled the report with the Cabinet Office said that the perpetrators of cyber crimes ranged from "state-sponsored" activists to organized crime gangs "teenagers sitting irregular in their rooms. "
Almost half of the £ 21 billion cost to business was made by the theft of intellectual property - including illegal downloading and file sharing. But industrial espionage, such as theft of designs and trade secrets, was also a significant problem.
The most affected sectors were pharmaceuticals, biotechnology, electronics, computers and chemicals.
