Opemipo Jaji, 18, subjected the schoolgirl to a three-hour ordeal and threatened to stab her after she tried to run away.
Jaji was found guilty of rape at the Old Bailey after the brave youngster gave evidence against him.
He had denied the offence, despite traces of the girl's blood being found on his clothes.
Jaji, of Edmonton, north London, had two previous convictions since the age of 16 involving an attack on a 12-year-old and for making indecent pictures of girls.
The schoolgirl was dragged into Jubilee Park, Enfield, north London, by Jaji in November. He had spotted her in her school uniform as she joked and laughed with a friend on a bus.
He followed her as she made her way home and attacked her in the dark park. One of the girl's gloves was stuffed in her mouth and the slightly built child was terrified during the attack as she was stripped.
She ran home after she was allowed to dress. Her parents were distraught when she turned up dirty and dishevelled, the court heard. They had called police when she failed to arrive home by 5.30pm. The child was taken to hospital and underwent an operation for an injury.
She told the court: "He kept saying, 'Stop moving or I will stab you'. I tried to run away but then he grabbed me when I got to the pavement of the park entrance.
"I kept on saying 'stop' because it was hurting me and he kept saying 'shut up' to me. He was just saying it every time I spoke.
"When I was on the floor, he said he would film me and send it into my school.
"I was saying 'Get off me, get off me, stop'."