Iain Freeman, 20, started chatting to the teenager on a site used by fans to swap messages and share photos.
The teenager – who later told police she had never even kissed a boy before – first agreed to have full sex with Freeman, who social workers warned was likely to re-offend, in a public toilet near Hearts football ground.
He was caught out when concerned members of the girl's family spotted picture messages from Freeman on her mobile phone, and police were called in.
At Edinburgh Sheriff Court today, Freeman was jailed for a year and put on the sex offenders' register for life. He also admitted sending sexually explicit video clips to her mobile phone.
Despite knowing the girl's age, he asked her to be his girlfriend and set up meetings at Hearts' home and away games.
Freeman, from Airdrie, first met the teenager at a match at Tynecastle but they did not speak because her parents were sitting beside her.
The pair began meeting in a public toilet in Gorgie where they eventually had sex in June 2007.
Procurator fiscal Ross McKay described how the girl, now 14, was a shy and quiet teenager who had never even kissed a boy before she met Freeman.
The girl had never had a boyfriend before Freeman, who was 19 at the time of the offence, asked her out. He said the girl still wanted to wait for Freeman and said the relationship between her and her parents had become strained.
But Freeman's defence solicitor, Colm Dempsey told the court there was no chance Freeman would meet with his victim again and said his client had faced up to what he had done.
And he told how his client had begun using the internet as a means of social interaction following the death of his mother.
Mr Dempsey added that Freeman had lost his job as a result of the offence and was anxious at the prospect of going to jail.
But Sheriff James Scott insisted only a custodial sentence would be suitable and ordered him to 12 months in custody with a further 18 on licence.