The woman reported she was attacked on the train on June 26 and was taken out on patrol with officers 12 days later.
While at Tottenham Hale station, she recognised a suspect and pointed him out to officers.
The man was arrested on suspicion of sexual assault and taken into custody.
He was then released on bail while enquiries continue.
A British Transport Police spokesperson said: “A woman reported that she was sexually assaulted by a man on a Victoria Line Underground train on Thursday 26 June.
“On Tuesday, 8 July officers took her out on patrol, and she spotted the man at Tottenham Hale station.
“She pointed him out to officers and he was quickly arrested on suspicion of sexual assault and taken into custody.
“He was later released on bail while enquiries continue.
“Anyone who is the victim of or witness to an offence on the rail network should text BTP on 61016, or call 0800 40 50 40. In an emergency always dial 999.”
