The cyber crime figures are a mid range estimate and the real cost could be much higher.
They are estimated to be made up of £21bn of costs to businesses, £2.2bn to government and £3.1bn to individuals.
Security minister Baroness Neville-Jones said the government was determined to work with industry to tackle cyber crime.
At the moment, cyber criminals are “fearless because they do not think they will be caught”, she said in a briefing in central London.
But efforts to get a grip on the problem had been hampered by firms who did not want to admit they had been the victims of attacks for fear of “reputational damage”.
This also meant that it was difficult to accurately estimate the cost to the economy – and the “worst case scenario” was likely to be much greater than £27bn.
“It is a bit like terrorism – the more you know the more frightening it looks,” said Baroness Neville-Jones.
But she said the government was not at “panic stations”, adding that it had a strategy to tackle the problem and had committed £650m over the next four years to it.
Baroness Neville-Jones said some of the cyber crime activity was “state-sponsored” but although the government had the ability to strike back it was “anxious not to get into a barney with friendly countries” over the issue.
It would instead focus its efforts on defending itself from cyber attack – which she said was the most effective strategy as it was often difficult to work out where the attacks were coming from.
“There are many companies in the country who do not know what the normal functioning of their systems looks like because they don’t actually know enough about their own systems,” she said.
There was also a problem with “assurance” – whether companies could trust staff not to leak commercial secrets to rivals.
Nearly half of the £21bn cost to business is made up of intellectual property theft – such as the theft of designs but not illegal file sharing, which is not included in the figure. Industrial espionage, such as the theft of commercial secrets, was also a significant problem.
Intellectual property theft cost £9.2bn, industrial espionage £7.6bn, this was followed by extortion, which cost £2.2bn, and direct online theft, which cost business £1.3bn. Some £1bn was lost through theft of customer data.
The hardest hit sectors were pharmaceuticals, biotech, electronics, IT and chemicals.