Figures reveal there were 411 sex offences committed against children in South Yorkshire last year - with 27 victims aged four or younger.
The NSPCC released the figures to show police forces across England and Wales recorded a child sex crime every 20 minutes last year.
Of the 23,000 offences recorded nationwide, including rape, incest and gross indecency, 411 were in South Yorkshire with 149 crimes committed against victims aged between five and 11 and 27 aged four or under.
According to South Yorkshire police statistics, 28 known suspects who committed offences were under 18.
The figures were supplied to the NSPCC under the Freedom of Information Act.
Detective Chief Superintendent Steve Talbot, head of specialist crime services at South Yorkshire Police, said: “The situation in South Yorkshire is in line with the rest of the country.
“Many offences against children are committed by other children and many offences are committed by adults within the family environment.
“In South Yorkshire we have dedicated staff working within our public protection units who deal with victims and investigate these reports.
“We also have a dedicated Sexual Assault Referral Centre for dealing with victims.
“Much of our work to keep children safe is done in partnership with other agencies, both statutory and voluntary.”