Former Big Brother winner Josie posted the photograph on Twitter, telling her followers that she will "hunt down the bullies" who beat him up.
Josie believes that her brother was attacked because he cannot hear, and it was later reported that he had used sign language when approached by 'at least two men'.
The pair were out celebrating Josie's 29th birthday when the shocking incident happened.
Josie tweeted: "Lost all faith in mankind tonight. I went to the toilet and my brother got beaten up for being deaf!!! What a disgusting world we live in!"
Sharing a picture of Harry, who lost his hearing as a baby after suffering from meningitis, Josie added: "I'm going to hunt the bullies who did this! The nicest guy ever was beaten up because they thought he was deaf & dumb."
Lost all faith in man kind tonight. I went to the toilet and my brother got beaten up for being deaf!!! What a disgusting world we live in!— Josie Gibson (@Josiestweet) January 26, 2014
After posting on Twitter, Josie and Harry were inundated with messages of support from both fans and celebrities.
Fellow Big Brother contestant Chanelle Hayes said: "That is the most disgusting, disgraceful, vile thing I've ever heard of. Some people are sick. Sending love to ur brother."
TOWIE star Ferne McCann added: "Sending your brother my love. This is disgusting behaviour. Makes me so sad. X"
An Avon and Somerset Police spokesman confirmed the force were aware of the incident.