British Transport Police (BTP) released the images of the woman after a 23-year-old man was subjected to the abuse on the Metropolitan Line.
PC Natalie Fairhurst said: “On the evening of Friday November 14, the victim was travelling on the Metropolitan line between Baker Street and Northwood London Underground stations.
“As the train approached Northwood, a woman opposite the man began shouting foul-mouthed homophobic abuse at him.
“She followed the victim off the train, haranguing him all the way to the station exit.”
Having examined CCTV footage from the evening, the police wish to speak with the woman in the image.
PC Fairhurst continued: “This abuse was entirely unprovoked and completely unacceptable.
“BTP is committed to ensuring the rail network remains a safe environment where all passengers and staff are treated with respect.
“We treat hate crime very seriously and will do everything in our power to find the person responsible.
“I think the woman in the image we are issuing today can help with our investigation. Do you know who she is?”
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference TSUB/B13 of 18/12/2014. Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.