The trial heard that he had spat at a man who had stepped in to protect two 19-year-olds who Dappy had started arguing with after they rejected his advances.
The jury was told that Dappy became angry, sparking the brawl, after the girls "dissed him" and called him boring.
Co-defendant Kieran Vassell, 25, of Hammersmith, west London, was also found guilty of affray and is to be sentenced alongside Dappy, as well as Alfred Miller, 28, of Brentford, west London, who pleaded guilty to affray.
A fourth defendant, Kalonji Stewart, 32, of Harborne, Birmingham, was found not guilty of the same offence.
Dappy faces a maximum sentence of three years' imprisonment for affray and six months for assault by beating.