CCTV footage shows the woman woman get knocked unconscious by a group of young men who proceed to pour drink over her.
The 22-year-old victim was sitting with a friend at the back of the bus – which was travelling towards south London in the early hours of the morning - when a group of five men got on and moved to where she was sitting.
One of the men is then said to have criticized the woman’s dress before pouring a can of drink over her head and pulling her hair.
She got up from her seat, but was pushed and then kicked in the stomach, as the gang laughed at her.
In the force of the blow, the woman fell to the floor of the bus and was knocked unconscious, while the men got off the bus and walked away.
Paramedics were called the scene and the woman was taken to St Thomas' Hospital with a head injury. She was treated and discharged a few hours later.
The attack happened on August 29, and Police have now released CCTV footage as part of their attempts to track the gang down.
Among the suspects was a man described as being around 20 years old, and was wearing a black T-shirt with a patterned pocket on the chest, dark trousers and a baseball cap worn back to front.
A Met Police spokesman said he was a light-skinned black man of slim build, and that the other four men in the group were also black.
Detective Constable Kyla Mulley, Lambeth CID, said: 'This was a shocking attack on a young woman, prompted by nothing more than a brief exchange of words.
'It is vital we track down this man and hold him to account for his behaviour.
'I am also keen to speak with other members of the group, who would be able to assist the investigation.'