On census night, there were 63,181,775 people living in the United Kingdom, the Office for National Statistics said.
The country has gained a net 4.1m people, or almost seven per cent, on the previous survey in 2001 – a rate of growth beaten only by the nine per cent population explosion after the Second World War.
Over the last 100 years, the UK population has increased by just over 50 per cent, the figures showed.
London attracted much of this growth, with the city’s headcount rising 12 per cent to 8.17m people in the decade.
Islington is the most densely population part of London, with 138.7 people per hectare, compared to an average across the 33 boroughs of 52 per hectare.
There are also more people than ever living in Scotland, after its population rose 4.4 per cent to 5.3m.
However, the number of Scottish over-65s grew at an even faster pace, rising from 15.9 to 16.8 per cent of the total population.
In the UK as a whole, the proportion of over-65s was steady at 16 per cent, rising from 9.4m to 10.4m people.
Around 50.4 per cent of the population is female, thanks to their slightly higher life expectancy.
In separate figures out yesterday, the ONS revealed that the average British lifespan was 85 for men and 89 for women in 2010. Since 1960, the average man has gained 10 years and the average woman eight years. The ONS used the modal age at death for these sums, stripping out infant mortality.