The jury found that Hussain, 56, had sexually assaulted a 14-year-old and a 15-year-old girl.
Sentence was deferred for background reports. Hussain's name was added to the sex offenders' register, the BBC reported.
The married restaurant owner, who held high-profile charity events with politicians, attacked a 15-year-old girl in 2002 and twice assaulted a 14-year-old girl last year.
Outside Perth Sheriff Court, the mother of one victim said: "This has been absolutely horrific for my daughter. I don't even think he is human. He showed no emotion in court. He tried to tarnish my daughter's name. Maybe now she can stop having nightmares about him."
Hussain was a driving force in Perth mosque and raised funds at an event with SNP MSPs John Swinney and Roseanna Cunningham after the 2005 Pakistan earthquake.
The court heard Hussain sexually abused a 15-year-old girl at the Al Farooq restaurant he owned in Perth city centre in November 2002.
He groped and fondled the girl before pushing her against a filing cabinet and fondling her breasts.
In July 2007, he indecently assaulted a 14-year-old girl at a Perth address, and attacked her again at another address in the town the following month.
His most recent victim, now 15, wept as she told the court Hussain forced himself upon her while she was helping him decorate a flat.
She said her chest was bruised as a result of the attack and told how she fled in tears into the arms of her mother.
The jury was told that Hussain said, "Do you know what this will do to me? You will ruin my life," as the girl, told him she was calling the police.
She said that Hussain then subjected her to a second indecent assault after being left alone with him at another Perth flat.
The girl said Hussain offered her money as she ran from the flat.
Police scientist Alistair Burt told the court that swabs taken from the girl's breasts revealed saliva that matched Hussain's DNA.