Jamie Seaton, 24, attacked the woman in the early hours of May 10 as she made her way home to the Hunter’s Bar area of Sheffield after an evening out with friends in the city centre.
According to South Yorkshire Police, he approached her as she walked along Endcliffe Vale Road, before grabbing her and dragging her into Endcliffe Park, where he assaulted her.
The attack was reported to police in the city within an hour and an investigation was launched by detectives.
Officers analysing footage from local CCTV cameras showed Seaton had followed his teenage victim from West Street in the city centre.
He was later arrested and charged with rape and two counts of assault by penetration on May 16 this year.
Seaton, of Burrowlee Road in Owlerton, admitted rape and two counts of assault by penetration at a hearing at Sheffield Crown Court yesterday.
Speaking afterwards, Detective Constable Jessica Hawley of South Yorkshire Police, who investigated the case, praised the young victim for her bravery.
She said: “Incidents like this are rare but they have a profound and lasting impact on victims.
“This was a violent and terrifying attack and I would like to praise the victim for the tremendous courage and dignity she has shown throughout the investigation.
“The fact Seaton pleaded guilty to the offence and did not force the victim to relive her ordeal in court is some small consolation.
“South Yorkshire Police takes all reports of rape extremely seriously and will work tirelessly to bring offenders to justice.
“We have specially-trained officers in place who work with victims from the moment a rape is reported, gathering every piece of evidence in order to secure a conviction.”
Seaton is expected to be sentenced for the offences by a judge at Sheffield Crown Court on October 29.
Pre-sentence reports will be carried out in advance of the hearing.