Its annual update showed 2.17m firms registered for tax in March, up 0.9 per cent or 18,000 on the year.
That takes the level past the previous highest number of 2.16m in 2008.
London is particularly strong, with 17.2 per cent of the total. Growth in the capital also led the country, with a 3.5 per cent rise, adding 13,000 businesses in the year. The south east came next with 15.7 per cent of all firms and a rise of 2,000 on March 2012.
There are 46,000 finance and insurance firms in the UK, a level which held steady on the year, with 18,500 in London and the south east.
The number of property firms increased 3,000 to 80,000, and professional, scientific and technical businesses rose 14,000 to 366,000.
The London Chambers of Commerce said the figures are an indication of the recovery.
“Dragon’s Den and The Apprentice have helped make business cool, and so has the ethnic factor,” said deputy chief Peter Bishop. “For instance the Indian business community is very active, with a great contribution to the London economy. And if you look at young people in the community, their role models are often business people.”
But the figures also reflect the number of zombie firms in the UK. Record low borrowing rates have allowed 100,000 businesses to remain in a state of living death, barely servicing their debts, according to the Association of Business Recovery Professionals.