Andrew Desborough, 44, was found guilty at Northampton Crown Court of seven counts of indecent assault against a child.
The court was told the offences were committed in the early 1990s and only came to light two decades later.
DC Mark Allbright from Northamptonshire Police’s child protection team said he welcomed the sentence handed down by the judge.
He said: “These offences came to light many years after they happened but we are pleased to have secured this conviction and potentially protected further vulnerable victims from harm.
“I hope today’s result gives the victim some comfort and I’d like to commend their bravery in coming forward.
“Northamptonshire Police takes all allegations of sexual abuse, non-recent or otherwise, very seriously and we would urge anyone with any concerns to contact us on Northamptonshire Police on 101.”