Gross domestic product had also expanded by 0.8 percent during the first quarter of the year, the Office for National Statistics said in a statement, confirming initial estimates provided last month.
GDP grew by 3.2 percent in the April-June period compared with the second quarter of 2013, slightly up on the initial estimate of 3.1 percent.
At 0.8 percent quarter-on-quarter, Britain's economy overtook the size it achieved before the global financial crisis of 2008.
While Britain's economy shows signs of solid recovery, growth in the 18-country eurozone ground to a halt in the second quarter, official data showed on Thursday, dragged down by France and Germany and casting a cloud over the crisis-hit region.