A Freedom of Information request to the Ministry of Justice found that in 2005, 1,363 people were convicted while in 2010, it was 2,135.
The rise has been attributed to better detection and raised awareness.
Child protection groups say the number is relatively small and that it remains a grossly under-reported crime.
NSPCC head of strategy and development Lisa Harker said: "It's difficult to tell if these figures indicate an increase in the number of sex offences being committed against children.
"It may be that more people - adults and children - are becoming aware of abuse and so are reporting cases to the police and other authorities.
"Nevertheless it's still a relatively small number of convictions considering child sex abuse is a big problem."
She said last year police in England and Wales were notified of more than 23,000 offences and that recent research by the NSPCC suggested one in 20 secondary school children had been sexually assaulted.
Donald Findlater from the Lucy Faithfull Foundation, a child protection charity which works with sexual offenders and organisations to help prevent abuse, said the increase in convictions could suggest courts were increasingly likely to find people guilty, even if the number of children reporting abuse remained the same.
However, if it indicated that children were feeling more confident to report a crime that in the past may have been too difficult, he was encouraged.
"They need to have the language skills to say what's happening to them and to understand it's wrong," he said.
"It's still the case that most children who are sexually abused do not report it."
Child Exploitation and Online Protection Centre (Ceop) chief executive Peter Davies said: "It is good news as it's a good indicator that police services and others are getting their act together."
He said police forces had changed how they investigated child sex abuse and officers have had specific training.
Mr Davies added that authorities did not use conviction numbers as a primary measure of success because it was an under-reported crime and hard to prosecute where there tended to be few witnesses.
The MoJ publishes statistics of sexual offences on children every quarter, however, it does not include children who are raped. These figures are included in the total of convictions for rape on all ages.
The figures obtained by the BBC cover all sex offences on children.
A Crown Prosecution Service spokesperson said the increase in prosecutions was because all the criminal justice agencies had made a concerted effort to offer support to victims throughout the process from the start of the investigation to giving evidence at trial.
This can include a special interview suite at the police station or a Sexual Assault Referral Centre (Sarc), screens in court or giving evidence through a video link, and support from a dedicated witness care unit.
Other figures released by the MoJ to the BBC under a Freedom of Information request show that up to January of this year, 281 people had been convicted of meeting a child following sexual grooming on the internet, since it was made illegal in 2004.
Source: Ministry of Justice
Separately, the Lucy Faithfull Foundation says calls by internet offenders to its helpline quadrupled since January 2005, from 124 calls to 493 in 2010.
Mr Findlater said the internet was changing sex offenders' behaviour by making access to the forbidden much easier.
"The internet has amplified and distorted human behaviour such as grooming," he said.
"Before the internet, offenders had to take significant risks, normally by leaving the country to take pictures. Most didn't think about it and didn't try."
Source: Ministry of Justice
And Mr Davies said: "Offending has always been there but the internet brings it into the open however it's also an investigative opportunity to find people as well. It's a double-edged sword."
An MoJ spokesperson said the Child Sex Offender Disclosure Scheme (where parents are able to discover if someone who has contact with their child is a convicted paedophile) which was rolled out to all police forces in England and Wales earlier this year was "a major step forward in our ability to protect children from sex offenders".
The spokesman added that the government will publish in the autumn an action plan to tackle child sexual exploitation, which will build on existing guidance and "our developing understanding of this dreadful abuse, including through local agencies' work around the country".
The number of people convicted of sex offences on children aged under 16 in England and Wales has increased by nearly 60% in six years.