The number of child sex offences reported to police across Wales rose to 2,069 last year - an average of five a day.
The figures - obtained by NSPCC Cymru / Wales - show a 43 per cent rise on 2013/14, when 1,446 sexual offences against children were recorded by Wales's four police forces.
Gwent Police saw the most significant increase, from 226 to 706 in 2014/15; a 212 per cent rise.
The other forces recorded the following figures, which were released to NSPCC Cymru / Wales under the Freedom of Information Act:
314 (13/14) 328 (14/15) 26.7% increase
299 (13/14) 328 (14/15) 9.7% increase
607 (13/14) 637 (14/15) 4.9% increase
A total of 364 victims - almost one a day - were aged 10 and under and 135 were aged just five and under. At least 68 victims were too young to attend school.
Each force was also asked for gender-based figures. Of those provided, more than five times as many offences were recorded against girls (1,242) than boys (214). Gwent Police could only supply gender details for 96 of its 706 recorded offences.
In 2013/14, 1,145 offences were recorded against girls and 229 against boys.
The figures may only reveal a small part of the whole picture, as many children are afraid to speak about their experiences. A recent NSPCC report also revealed some young victims say they are not believed when they report sex crimes to police.
Across England and Wales the number of recorded child sexual offences soared by a third compared to last year, with more than 41,000 sex crimes inflicted upon young people.
A reason for the significant increases remains unclear. However, the NSPCC believes victims may now feel more confident about coming forward following greater awareness about sexual abuse. Police forces may have improved their recording methods or become more vigilant about sexual crimes. High-profile historic cases may have also encouraged survivors to speak out.
With such a dramatic increase in recorded sex crimes, there has never been a greater need for therapeutic help for victims. NSPCC Cymru's It's Time campaign is calling on the Welsh government to prioritise recently announced additional funding for Child and Adolescent Mental Health Services (CAMHS) to children who have been abused.
Head of NSPCC Cymru / Wales, Des Mannion, said: "These figures paint a very worrying picture of just how extensive these appalling crimes have become.
"A huge rise across Wales is clearly troubling and we will seek to understand why offences in Gwent have trebled in the space of a year.
"Where better recording of this crime has at least contributed to an increase, police forces must be applauded and we wholeheartedly welcome any boost in confidence that is helping victims to come forward.
"While high-profile cases may dominate the headlines, we must not forget that around 90 per cent of sex offences against children are committed by someone they know - a relative, a family friend or an acquaintance.
"Now more than ever Wales needs easy access to the right treatments. We want to see an end to long delays and our It's Time campaign calls for mental health service funding to be targeted at abused children."