80-year-old Koji Takeuchi admitted abusing the three-year-old in her home over a period of six years, four decades ago.
Sussex Police safeguarding detectives told how Koji Takeuchi, now of Trent Lane, North Clifton near Newark, Notts, held meditation sessions with the girl's parents and told them he would look after her so they could sleep, but subjected her to sexual abuse for several years.
Takeuchi, who also gives his professional name as Buddha Maitreya, was sentenced at Hove Crown Court on Friday 30 October, after admitting sexual assaults on the girl, then aged between three and nine, between 1975 and 1981.
He was given two consecutive three-year sentences with an additional one year extended licence for each of them, plus two years extended custody.
The court also imposed an indefinite Sexual Harm Protection Order barring him from working with vulnerable adults or children for life, and he will be a registered sex offender for life.
Detective Constable Stewart Cameron of the Brighton Safeguarding Investigations Unit said:
"Takeuchi used his trusted position as a monk to ingratiate himself with this family and under the guise of hosting meditation sessions there he swiftly groomed this very young and vulnerable girl and systematically abused her for his own sexual gratification for a long time.
"He made her believe that they were girlfriend and boyfriend and that this was their secret, until Takeuchi abruptly broke off the relationship.
"This terrible experience robbed the victim of her childhood and has had a lasting impact on her life.
"Eventually in 2018 she summoned up the resolve and strength to come forward and fully disclose to us what had happened to her all those years ago.
"This investigation is another example of the way we will always follow up such reports, regardless of how long ago the events are said to have occurred, to support the victim and seek justice for them wherever possible."
For sources of advice and support and how to report sexual offences, see the Sussex Police website.