Police have praised the victim for coming forward.
Julian Harriss, of Britannia Road, Banbury, admitted three counts of engaging in sexual activity in the presence of a child at Oxford Crown Court.
The 51-year-old intentionally carried out the offences between 2010 and 2020, when his victim was a girl under the age of 16.
He was sentenced to 21 months’ imprisonment on Monday, and was made the subject of a sexual harm prevention order for 10 years after his release.
Investigating officer, Detective Constable Kelly Gilbert, said: “Harriss engaged in sexual activity in front of a child which is a criminal offence and had an impact that stayed with the victim.
“I would like to thank the victim for coming forward and reporting this to us. This has been a lengthy investigation for the victim.
“We would encourage anyone who has been a victim of a sexual offence to please report no matter the length of time that has passed.
“It will be investigated and we will always look to work with the CPS to bring offenders such as Harriss to justice.”
Anyone who wishes to report a sexual offence should call 101 or 999 if it is an emergency.