Mahad Yusuf, 20, and Fesar Mahamud, 19 pleaded guilty to human trafficking offences on 5 December.
The 19-year-old victim was told she “belonged” to Yusuf as she was lured into a car and driven to Swansea.
Known as “county lines”, gangs use other people to traffic drugs for them remotely via dedicated mobile phones.
Det Insp Rick Stewart said: “The victim in this case suffered a horrendous ordeal at the hands of these two men, who trafficked her for their own criminal gain.
Yusuf, of Cuckoo Hall Lane, Edmonton, and Mahamud, of Zambezie Drive, Edmonton also pleaded guilty to conspiracy to supply cocaine and heroin.
The pair will be sentenced at Swansea Crown Court on 4 January.