Carl Johnson was sentenced on Thursday after being found guilty at Kingston Crown Court last month of eight counts of indecent assault, following a five-day trial.
The 53 year old of Bowden Drive in Sydenham targeted his victim between 1991 and 1995 when she was aged between 13 and 15.
Detective Sergeant Amanda Kearsley of the Child Abuse and Sexual Offences Command, said: "Johnson is a predatory offender who deliberately targeted a vulnerable child."
Mr Johnson used his position at a church in Battersea to groom the young girl, before going on to commit multiple sexual offences against her.
DS Kearsley added: "Johnson was part of the same church community as the victim and he should have been there to provide support; instead he groomed her before committing offences over a prolonged period."
"This has been a long and emotional process for the complainant. I would like to praise her courage and commitment to making sure Johnson was convicted. She has ensured he is no longer a risk to other young people."
Police immediately launched an investigation after the victim came forward in 2014 to tell officers about what had happened to her.