Hannah Squire, prosecutor in the case, told Swindon Crown Court how the teenager first watched 29-year-old Andy Hammersley perform at a gig in 2013.
Following the performance, Hammersley shouted out his social network details.
Speaking in court, Miss Squire said: “This was picked up by the victim and she got in touch with him via his Facebook account. It is from there that the contact took place.
“Quite early on the girl’s mum became aware that they were contacting each other. She did send him a message to tell him to stop, which he did not do.”
Following an exchange of messages, the young teenager met Hammersley on two occasions between 2013 and 2014.
The police were called after the girl disappeared and spent the night with him in a Bristol hotel.
Jailing him Judge Peter Blair QC said “You face two counts of sexual activity with a child under 16. The feature of there being two such occasions aggravates matters. It is not totally isolated.
“What makes it worse still was you were to ignore a warning letter from the girl’s mum to stop any contact with her.”
Hammersley has been banned from having unsupervised contact with girls under the age of 16, and has been placed on the sex offender’s list.