Grahame Humphries, 71, of Charlbury, Oxfordshire, was told he abused his position by kissing and touching the teenager 45 years ago.
Humphries was sentenced to eight months in prison, suspended for two years.
He most recently worked in Blockley in the Cotswolds, before retiring in 2012.
Sitting in Kingston Crown Court, Judge Paul Dodgson heard the girl's family had been looking after Humphries while his pregnant wife was away.
He admitted kissing the girl and touching her breasts over her clothes on a number of occasions between September 1971 and September 1972.
Another such incident saw him enter the girl's bedroom when she was home alone and insist she take her clothes off, prosecutor Max Hardy said.
The victim refused and later told her mother what had been happening, he added.
Judge Dodgson told the pensioner, who entered the dock with the aid of crutches, he had blighted his victim's life while working in another parish.
He said: "Forty-five years ago when you were a young curate aged 27 you did something very wicked. You took advantage of your position of trust."
Mr Hardy said the case came to court after the victim decided to go to police following "extensive publicity" around the Jimmy Savile scandal.
Humphries, who has worked in parishes across England, was told to pay Â£500 costs and given a 24-month supervision order.
He was ordered to sign the sex offenders register for the next five years.
A retired vicar who committed a "wicked" crime by indecently assaulting a 14-year-old girl while his wife was pregnant has been convicted of indecent assault.