Hoopong Wong, 25, admitted to stabbing Karlos Frederick five times, but claimed it was an accident. However, the unanimous jury found him guilty at 3.40pm at Kingston Crown Court on Monday.
Mr Wong, of Byron Way, Middlesex, will be sentenced on December 7.
Darren Henry, 24, of Barmouth Avenue, Middlesex, who was jointly charged with the stabbing, has been cleared of the charge. Mr Henry was accused of punching Mr Frederick while Mr Wong stabbed him.
The court heard the incident, which happend on May 20 this year, started with an argument between Mr Wong and Mr Frederick which led to a fight where the two men rolled down the stairs at the nightclub.
Mr Wong then spotted a knife on the floor, which he picked up because he was worried it might be used against him.
He told the court while giving evidence last week: “I panicked because at the time I was worried that it [the knife] would be taken off me and used against me.”
The jury had been told last week about Mr Wong’s previous convictions of carrying a knife in a public place in 2006 and 2007. Mr Wong however, assured that he had changed since then.