Model agency boss Dawie de Villiers was on Wednesday found guilty of 32 of 38 charges, including raping a child and sexual assault, Netwerk24 reported.
De Villiers, 36, dressed in a black suit with a red shirt, joked with a friend before his appearance in the High Court in Johannesburg. De Villiers shook his head as the verdict was delivered.
Judge Cassim Moosa said De Villiers was a poor witness and considered the minor's testimony to be credible, clear, and concise.
"She insisted throughout the trial that he had raped her," Moosa said.
All the evidence presented to the court left him with no other choice but to find De Villiers guilty on charges of rape, sexual assault, fraud, exposing children to pornography, and accessing child pornography.
De Villiers had claimed that the State witnesses lied and conspired with investigative journalism TV programme Carte Blanche to harm his and his agency's reputation.
He denied that he had sex with a minor.
One of the minors testified that De Villiers had asked her to take off her clothes in front of him. He claimed she was only engaged in method acting.
De Villiers said he did not stop her from taking off her clothes, as it was sensual and sexy, and he thought she wanted to do it.
Moosa accepted the minor's testimony over that of De Villiers because his version had too many contradictions.
After his conviction, prosecutor Arveena Persad asked that his bail be revoked. Moosa ruled that De Villiers had to pay an additional R5 000 bail.
Sentencing proceedings will begin on March 8.