Bangladeshi Sujon Uddin, 20, and an accomplice subjected their victim to a terrifying hour-long ordeal during which she was raped twice by both men.
At one point the 18-year-old was pinned down by the unidentified male - known only as 'Rex' - while Uddin forced himself on her.
The teenager was also forced to perform sex acts on Rex during the attack which took place in Mile End Park, in Bow, east London.
Snaresbrook Crown Court heard the woman, who cannot be identified for legal reasons, had met the two men in the park in the early hours of August 21, 2010.
She was heard to suffer from epilepsy and had she suffered several episodes during the incident.
Sending Uddin to a Young Offenders Institution Judge Timothy King said: 'Your companion perpetrated a number of sexual activities, including rape, against this woman while you stood nearby
'There came a stage after the victim had been raped by Rex that he then called you over, inviting you to have sexual activity with his victim.
'You decided that you would and so it was that this young woman having been raped by Rex was then held down by him while you raped her.'
The court heard that after Uddin had raped the teenager once the second male attempted to rape her again before Uddin attacked her a second time.
Judge King continued: 'It was an ordeal that lasted for her for about one hour.
'She apparently made it clear that she was unwilling to have any physical or sexual contact with you or your companion.
'You had no regard whatsoever; it may be you were affected by alcohol at the time, to the wishes of this young woman.
'She was clearly traumatised by this offence.
'Moreover she was an epileptic and claims that she suffered several episodes during the attack upon her.
'This was a repeated rape of the same victim over a period of time involving multiple assailants.
'Those in themselves are serious aggravating features.
'Clearly she was held against her will.'
Uddin had arrived in the UK with his mother in 2006.
Prosecutor Julian Jones said: 'He was born in Bangladesh and came to this country about five years ago.
'He entered the UK on a visitors' visa and then unsuccessfully claimed for asylum.
'He is now liable for deportation.'
Uddin, of no fixed address, admitted two counts of rape on the first day of his trial in May.
