The Office for National Statistics said gross domestic product grew by 0.8 percent in the three months through June compared with the previous quarter. It expanded 3.1 percent over the year, putting it 0.2 percent ahead of its pre-crisis peak in early 2008.
The global financial crisis triggered a deep downturn for the British economy. By mid-2009, GDP was more than 7 percent below its pre-recession level.
Treasury chief George Osborne said Friday's figures marked a "major milestone in our long-term economic plan."
On Thursday, the International Monetary Fund predicted that Britain's economy would grow by 3.2 percent this year, making it the fastest-growing among major industrialized nations.
Opposition politicians and some analysts warned that the recovery is built on shaky foundations. Much of the GDP growth was in the services sector, which expanded by 1 percent. Manufacturing grew by 0.2 percent, while construction shrank by 0.5 percent.
"The U.K. economy isn't as strong as it looks," said Ben Brettell, senior economist at stockbrokers Hargreaves Lansdown. "While it has surpassed its pre-crisis peak in absolute terms, a larger population means GDP per capita is around 6 percent lower."
In another sign of returning financial-sector confidence, the Royal Bank of Scotland announced Friday that its pre-tax profits nearly doubled to 2.65 billion pounds ($4.5 billion) in the first half of the year. RBS was bailed out by the British government during the crisis and remains 81 percent owned by taxpayers. Its shares jumped over 13 percent after the earnings report.