Last year saw the largest annual increase in adoptions in 15 years, with 5,206 in England and Wales.
The figure represents a 9.8% increase on 2011 when there were 4,740 adoptions, said the Office for National Statistics (ONS).
In 2012, nearly two-thirds of children adopted (63%) were aged between one and four years, rising from 62% in 2011. The percentage of children adopted who were born outside of marriage increased slightly to 85% in 2012, up from 82% the year before.
The latest figures from the ONS are made up of adoptions which took place following court orders in England and Wales in 2012 and apply to adoptions by relatives and step-parents as well as adoptions from care.
In 2012, 51% of children adopted were male and 49% were female, the exact opposite of the year before. The percentage of children being adopted between the ages of one and four has increased steadily since 1998 when just 34% of children adopted were of those ages.
In contrast, the percentage of children adopted aged from 10 to 14 has more than halved from 21% in 1998 to 8.4% in 2012.
The number of children being adopted in other age groups has also gone down: in 2012, 24% of children adopted were aged five to nine and 3.2% were aged 15 to 17, down from 36% and 5% respectively in 1998.
Wales recorded a 12% increase in adoptions in 2012 with 371 children entered into the Adopted Children Register, while in England there was a 9.6% rise with 4,835 children registered.
The ONS suggested the rise could be down to a recent drive to improve the adoptions process in England and in Wales. In May last year the Government launched new scorecards for local authorities that lay bare how long they take to find adoptive parents for children in care.
More recently it announced there will be a ''fast-track'' system for previously-approved foster carers and adopters, along with legal obligations on adoption agencies to refer would-be adopters to the Adoption Register within three months of approval.