Ahmad Mulakhil, 23, was convicted after a trial at Warwick Crown Court of one count of raping a child under 13 in Nuneaton, central England, last July.
He had previously pleaded guilty to a further count of rape of a child under 13 and was also found guilty of abducting a child, sexual assault and making indecent images of a child by filming the victim.
Judge Kristina Montgomery said the victim had told Mulakhil that she was 19 years old but that there was "no doubt that you knew she was aged under 16".
She sentenced Mulakhil to 15 years in prison, which she said "renders you automatically liable for deportation".
Mulakhil, who came to the UK on a small boat four months before the offences last July, showed no emotion and stared ahead at the barristers and the judge during the hearing, appearing to be listening intently to the interpreter sitting in the dock.
His lawyer said Mulakhil arrived in the UK when he was 22 after fleeing Afghanistan.
"He was planning on attending university to study economics but for a variety of reasons, he came under the focus of the Taliban, as did his family, and that is the reason he ultimately fled the country.
"His brother did the same, ultimately ending up in another country. He entered this country and when he arrived, claimed political asylum and was awaiting determination of that claim."
Mulakhil told police he believed the girl was 19 and that she had initiated what was his first sexual encounter.
Anti-immigration activists have seized on other criminal cases involving asylum seekers, predominantly young men and particularly those housed in hotels, to argue that they are a danger to nearby communities.
Pro-migrant groups, however, have said ultranationalist groups and opportunistic politicians are deliberately seeking to exploit and inflame tensions for their own ends.
A protest took place outside the court prior to and during the hearing, with a banner being draped over railings leading to the court which read: "Stop the invasion, end immigration."
The man's attacks initially triggered large-scale protests in Nuneaton.
with PA
