The incident occurred on a route 36 bus from Victoria Train Station around 12pm on Thursday, April 28.
A man boarded the bus through the back exit on the bottom floor, sat next to the victim, who was standing near the window and sexually touched her.
The man sexually touched the victim again as she changed seats after she got up and moved.
The victim moved away from the suspect, but he continued to stare at her and attempted to converse with her.
The man got off the bus in Park Lane and continued to stare out the window at her. A few minutes later, the victim exited the bus.
The MPS and our partners at TFL are heavily committed to tackling sexual abuse on the bus network,” said Detective Superintendent Michael Dougall. Nobody should have to go through this ordeal while going about their daily business. I would urge anyone with information about this crime to contact the police as soon as possible.
Any witnesses or anyone with information are asked to contact police at 101 or via Twitter @MetCC.
To provide information anonymously, call Crimestoppers at 0800 555 111 or go to crimestoppers-uk.org.
More news from Victoria