The population of England and Wales increased by 7% between the last two census surveys, the largest growth in numbers seen in any period since records began, the Office for National Statistics (ONS) said.
There were 56.1 million people living in England and Wales on the day of Census 2011, an increase of 3.7 million since 2001, when there were 52.4 million people.
Figures also showed that one in six people in England and Wales in 2011 was aged 65 and over.
The survey paints a picture of an ageing population, with 430,000 people in England and Wales aged 90 and over, compared with only 13,000 when the Census was carried out 100 years earlier in 1911.
The median age of the population has increased to 39 in 2011, up from 35 in 2001 and 25 in 1911.
But there was also an increase in the number of under fives, with more than 400,000 more in 2011 compared with 2001.
The ONS results show that every region in England and Wales had a larger population in 2011 than 10 years earlier.
The largest increase in population was in London, which grew by 12%, gaining more than 850,000 inhabitants and taking its total population to more than eight million.
Figures showed that on Census day, which took place on March 27 last year, the number of women over 90 was 315,000, nearly three times higher than the number of men over that age, at 114,000.
The total population figure was about half a million larger than estimates had shown a year earlier. The population of England was 53 million while Wales was 3.06 million. The population of Northern Ireland also increased to 1,801,900, an increase from around 1.7 million in 2001. Figures for Scotland will be released later this year.