Police have hailed a "safe and trouble-free" start to the Night Tube, after just one person was arrested.
The 17-year-old boy was arrested on a Victoria line platform at Oxford Circus at 2am on Sunday on suspicion of possession of drugs and carrying a bladed article.
He remains in police custody.
Around 100 officers patrolled the Central and Victoria lines as the long-heralded Night Tube finally launched in the early hours of Saturday.
The British Transport Police said there were no reported offences targeting the public or rail staff on trains or stations, which remained open between 12.30am and 5am on Saturday and Sunday.