The previously unknown 1,700-year-old fragment of papyrus is said to quote him referring to a wife.
US expert Karen King said it is the only text to suggest a marriage — as in hit book The Da Vinci Code.
The excerpt, written in ancient Egyptian Coptic, reads: “Jesus said to them, ‘My wife — she will be able to be my disciple’.”
It appears to add: “I dwell with her.”
The woman is thought to be his disciple Mary Magdalene, said by some to have been a repentant prostitute.
The belief that Jesus never married gave rise to the celibate priesthood in the Catholic church.
Harvard professor Ms King believes the text is a copy of a gospel probably written in Greek in the second century.
She said: “Christian tradition has long held that Jesus was not married — even though no reliable historical evidence exists to support that claim.”
However, she stressed that the newly-found script did not prove for certain that Jesus was married.
Bible scholar Ben Witherington also urged caution.
He said texts of the period used “the language of intimacy” for spiritual relationships.